Improve opa filter benchmarks

[mefarazath]

This PR introduces changes to,

• Run opa filter benchmarks with and without decision logs
• Run the benchmarks in parallel to possibly detect contention issues and overall performance under load
• Measure percentiles in benchmark tests (inspired by Print percentiles in benchmark  #2699)

[mefarazath]

Sample benchmark run measuring percentiles

go test -benchmem -run=^$ -bench ^BenchmarkAuthorizeRequest$ -benchtime=3s

BenchmarkAuthorizeRequest/minimal/no-decision-logs-10         	  653377	      4862 ns/op	   26142 B/op	     487 allocs/op
BenchmarkAuthorizeRequest/minimal/no-decision-logs/P50-10     	  653377	     31459 ns/op
BenchmarkAuthorizeRequest/minimal/no-decision-logs/P99.5-10   	  653377	    396833 ns/op
BenchmarkAuthorizeRequest/minimal/no-decision-logs/P99.9-10   	  653377	    710041 ns/op

BenchmarkAuthorizeRequest/minimal/with-decision-logs-10       	   62737	     51580 ns/op	   79947 B/op	    1331 allocs/op
BenchmarkAuthorizeRequest/minimal/with-decision-logs/P50-10   	   62737	     97250 ns/op
BenchmarkAuthorizeRequest/minimal/with-decision-logs/P99.5-10 	   62737	  15023917 ns/op
BenchmarkAuthorizeRequest/minimal/with-decision-logs/P99.9-10 	   62737	  15544875 ns/op

BenchmarkAuthorizeRequest/with-body/no-decision-logs-10       	  335612	     78599 ns/op	   35122 B/op	     513 allocs/op
BenchmarkAuthorizeRequest/with-body/no-decision-logs/P50-10   	  335612	    590375 ns/op
BenchmarkAuthorizeRequest/with-body/no-decision-logs/P99.5-10 	  335612	   3332458 ns/op
BenchmarkAuthorizeRequest/with-body/no-decision-logs/P99.9-10 	  335612	   4318250 ns/op

BenchmarkAuthorizeRequest/with-body/with-decision-logs-10     	   61664	     63934 ns/op	   91055 B/op	    1404 allocs/op
BenchmarkAuthorizeRequest/with-body/with-decision-logs/P50-10 	   61664	    240916 ns/op
BenchmarkAuthorizeRequest/with-body/with-decision-logs/P99.5-10	   61664	  14367416 ns/op
BenchmarkAuthorizeRequest/with-body/with-decision-logs/P99.9-10	   61664	  15672583 ns/op

BenchmarkAuthorizeRequest/jwt-validation/no-decision-logs-10  	          211809	     16336 ns/op	   60280 B/op	     964 allocs/op
BenchmarkAuthorizeRequest/jwt-validation/no-decision-logs/P50-10	  211809	    103541 ns/op
BenchmarkAuthorizeRequest/jwt-validation/no-decision-logs/P99.5-10	  211809	   1552625 ns/op
BenchmarkAuthorizeRequest/jwt-validation/no-decision-logs/P99.9-10	  211809	   2376417 ns/op

BenchmarkAuthorizeRequest/jwt-validation/with-decision-logs-10         	   47227	     74450 ns/op	  122129 B/op	    1808 allocs/op
BenchmarkAuthorizeRequest/jwt-validation/with-decision-logs/P50-10     	   47227	    217292 ns/op
BenchmarkAuthorizeRequest/jwt-validation/with-decision-logs/P99.5-10   	   47227	  16026917 ns/op
BenchmarkAuthorizeRequest/jwt-validation/with-decision-logs/P99.9-10   	   47227	  17956916 ns/op

[szuecs]

best would be to show benchstat results like #2876
you need 2 files for example old.txt and new.txt to compare old vs new.

[AlexanderYastrebov]

best would be to show benchstat results like #2876

See https://pkg.go.dev/golang.org/x/perf/cmd/benchstat

[mefarazath]

@szuecs @AlexanderYastrebov

Apologies for the confusion. This PR simply improves the existing benchmark code to add more measurements to get better insights into latency distribution and does not add anything to improve the performance. Added sub benchmarks also helps us to get an idea for each scenario with and without decision logging enabled.

This would gives us a quick way to verify/validate performance improvements proposed to filter and opa with better clarity.

As an example I did a comparison between v0.68.0 (current version in skipper) vs a PoC done by OPA team to improve decision logs performance. The p995 and p999 gave a better idea on the impact of the improvements here.

➜  benchmark-results benchstat v0.68.0.txt after_fix.txt                                                                                                                              7ms
goos: darwin
goarch: arm64
pkg: github.com/zalando/skipper/filters/openpolicyagent/opaauthorizerequest
cpu: Apple M1 Max
                                                            │  v0.68.0.txt   │            after_fix.txt             │
                                                            │     sec/op     │    sec/op     vs base                │
AuthorizeRequest/jwt-validation/with-decision-logs-10           70.05µ ±  1%   22.51µ ±  2%  -67.87% (p=0.000 n=10)
AuthorizeRequest/jwt-validation/with-decision-logs/P50-10       201.6µ ±  3%   192.5µ ±  2%   -4.52% (p=0.000 n=10)
AuthorizeRequest/jwt-validation/with-decision-logs/P99-10     15299.9µ ±  1%   654.3µ ±  4%  -95.72% (p=0.000 n=10)
AuthorizeRequest/jwt-validation/with-decision-logs/P99.5-10   15798.8µ ±  1%   780.5µ ±  4%  -95.06% (p=0.000 n=10)
AuthorizeRequest/jwt-validation/with-decision-logs/P99.9-10    16.547m ±  1%   1.226m ± 33%  -92.59% (p=0.000 n=10)
geomean                                                         818.0µ         345.9µ        -57.71%

                                                      │  v0.68.0.txt  │            after_fix.txt             │
                                                      │     B/op      │     B/op      vs base                │
AuthorizeRequest/jwt-validation/with-decision-logs-10   119.34Ki ± 0%   89.59Ki ± 0%  -24.93% (p=0.000 n=10)
geomean                                                  59.12Ki        49.91Ki       -15.58%

                                                      │ v0.68.0.txt │             after_fix.txt             │
                                                      │  allocs/op  │  allocs/op   vs base                  │
AuthorizeRequest/jwt-validation/with-decision-logs-10   1.809k ± 0%   1.520k ± 0%  -15.98% (p=0.000 n=10)
geomean                                                  966.2         864.7       -10.50%
¹ all samples are equal

[AlexanderYastrebov]

Why not require.NoError(t, err) here and below?

[AlexanderYastrebov]

Please use require.* (require.NoError in this case) to check preconditions and stop test early and assert.* to verify expected outcomes being tested.

[AlexanderYastrebov]

Couple of nits should be fixed, otherwise looks ok.
Please also squash into a single commit with a detailed commit message.