[SDTEST-437] Auto test retries for RSpec

[anmarchenko]

What does this PR do?
Adds auto test retries functionality for RSpec test framework

How to test the change?
Tested using middleman test suite with this flaky test:

    it "is new flaky" do
      res = rand(3)
      expect(res).to eq 1
    end

Locally test process completed normally:

Results of the test run in Datadog

New flaky test detected:

All the retries are correctly displayed in Datadog test runs:

Test session has status "pass":

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 98.89%. Comparing base (f00caf6) to head (9e6f62e).
Report is 12 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #213      +/-   ##
==========================================
+ Coverage   98.84%   98.89%   +0.04%     
==========================================
  Files         253      261       +8     
  Lines       11630    12096     +466     
  Branches      521      544      +23     
==========================================
+ Hits        11496    11962     +466     
  Misses        134      134              

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

[devinburnette]

if we're delaying the reporting until after the retries, then isn't it true that we would potentially hide the fact that there were flakes? or will the final trace data include the flake information?

[anmarchenko]

This is hiding reporting (for now) to RSpec formatter that prints the final message and tracks tests that failed (I might fix it in later versions to format retries correctly).

As tested in instrumentation_spec every retry is traced as a separate test span, so the test will be correctly identified as flaky. Also, test suite and test session statuses will be correctly reported as pass.