chore: Adds staticcheck and unused lint check

[gruyaume]

Description

Enables the staticcheck and unused lint checks and makes the necessary changes to satisfy those.

[onf-bot]

Can one of the admins verify this patch?

[onf-bot]

Can one of the admins verify this patch?

[gab-arrobo]

ok to test

[gab-arrobo]

+1

[gab-arrobo]

FYI, I know io/ioutil is deprecated. So, os should be used instead, but for some reason I do not see that this change is needed for the lint check to pass when staticcheck and unused are enabled

[gruyaume]

This is strange, here's the golang ci output when I enable those checks and prior to making the changes:

guillaume@potiron:~/code/udr$ golangci-lint run -v --config ./.golangci.yml
INFO [config_reader] Used config file .golangci.yml 
INFO [lintersdb] Active 14 linters: [asciicheck bodyclose dogsled godox gofmt govet ineffassign misspell nakedret noctx predeclared staticcheck unconvert unused] 
INFO [loader] Go packages loading at mode 575 (types_sizes|deps|files|imports|name|compiled_files|exports_file) took 142.052844ms 
INFO [runner/filename_unadjuster] Pre-built 0 adjustments in 3.366162ms 
INFO [linters_context/goanalysis] analyzers took 178.55217ms with top 10 stages: buildir: 102.73302ms, buildssa: 55.782148ms, gofmt: 1.216444ms, nilness: 1.179526ms, fact_purity: 1.0634ms, misspell: 939.943µs, SA5012: 916.323µs, fact_deprecated: 884.799µs, printf: 858.124µs, typedness: 850.968µs 
INFO [runner] Processors filtering stat (out/in): max_same_issues: 4/4, path_prettifier: 4/4, diff: 4/4, skip_dirs: 4/4, identifier_marker: 4/4, exclude: 4/4, uniq_by_line: 4/4, max_per_file_from_linter: 4/4, severity-rules: 4/4, filename_unadjuster: 4/4, skip_files: 4/4, sort_results: 4/4, autogenerated_exclude: 4/4, path_prefixer: 4/4, nolint: 4/4, max_from_linter: 4/4, source_code: 4/4, path_shortener: 4/4, fixer: 4/4, cgo: 4/4, exclude-rules: 4/4 
INFO [runner] processing took 676.194µs with stages: nolint: 489.072µs, identifier_marker: 57.408µs, autogenerated_exclude: 38.8µs, source_code: 33.463µs, path_prettifier: 27.734µs, skip_dirs: 11.985µs, skip_files: 6.97µs, cgo: 2.341µs, max_same_issues: 1.969µs, uniq_by_line: 1.312µs, path_shortener: 1.078µs, max_from_linter: 902ns, severity-rules: 753ns, filename_unadjuster: 717ns, max_per_file_from_linter: 629ns, fixer: 263ns, exclude-rules: 236ns, diff: 190ns, exclude: 174ns, sort_results: 113ns, path_prefixer: 85ns 
INFO [runner] linters took 250.163303ms with stages: goanalysis_metalinter: 249.434163ms 
factory/factory.go:15:2: SA1019: "io/ioutil" has been deprecated since Go 1.19: As of Go 1.16, the same functionality is now provided by package [io] or package [os], and those implementations should be preferred in new code. See the specific function documentation for details. (staticcheck)
        "io/ioutil"
        ^
service/init.go:46:3: field `heartBeatTimer` is unused (unused)
                heartBeatTimer string
                ^
service/init.go:368:4: SA4006: this value of `err` is never used (staticcheck)
                        nfProfile, err = udr.BuildAndSendRegisterNFInstance()
                        ^
service/init.go:372:3: SA4006: this value of `err` is never used (staticcheck)
                nfProfile, err = udr.BuildAndSendRegisterNFInstance()
                ^
INFO File cache stats: 5 entries of total size 24.8KiB 
INFO Memory: 5 samples, avg is 77.9MB, max is 161.3MB 
INFO Execution took 398.976934ms