[PROF-9180] Benchmarks for allocation profiling

[AlexJF]

What does this PR do?
Adds sample+serialize ruby microbenchmark and a benchmarking platform configuration focused on allocation profiling.

Motivation:
Understand overheads of allocation profiling.

How to test the change?

Microbenchmark

❯ bundle exec ruby benchmarks/profiler_memory_sample_serialize.rb
Libdatadog from: /Users/alexandre.fonseca/Projects/DataDog/libdatadog/build/arm64-darwin-23/lib/pkgconfig
Current pid is 48717
DogStatsD reporting ❌ disabled
Warming up --------------------------------------
sample+serialize 
                         1.000  i/100ms
Calculating -------------------------------------
sample+serialize 
                          4.526  (± 0.0%) i/s -     46.000  in  10.164368s

Benchmarking platform

For Datadog employees:

• If this PR touches code that signs or publishes builds or packages, or handles
  credentials of any kind, I've requested a review from @DataDog/security-design-and-guidance.
• This PR doesn't touch any of that.

Unsure? Have a question? Request a review!

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 98.23%. Comparing base (81e6060) to head (42dbcbd).

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #3477   +/-   ##
=======================================
  Coverage   98.23%   98.23%           
=======================================
  Files        1275     1275           
  Lines       75167    75169    +2     
  Branches     3548     3548           
=======================================
+ Hits        73842    73844    +2     
  Misses       1325     1325           

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

[ivoanjo]

👍 LGTM