chore: remove compat.stringify usage from gunicorn test

[wantsui]

While reviewing gunicorn's flaky tests with @brettlangdon , we found that compat stringify doesn't exist leading to errors such as https://gitlab.ddbuild.io/DataDog/apm-reliability/dd-trace-py/-/jobs/692703418:

    def gunicorn_server(gunicorn_server_settings, tmp_path):
        cfg_file = tmp_path / "gunicorn.conf.py"
        cfg = build_config_file(gunicorn_server_settings)
>       cfg_file.write_text(compat.stringify(cfg))
E       AttributeError: module 'ddtrace.internal.compat' has no attribute 'stringify'. Did you mean: 'StringIO'?

The closest is maybe_stringify, added in this PR: https://github.com/DataDog/dd-trace-py/pull/2465/files

This PR removes the compat.stringify usage and removes the flaky marker.

Also related to efforts in #11274 .

Checklist

• PR author has checked that all the criteria below are met
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• The PR description articulates the motivation for the change
• The change includes tests OR the PR description describes a testing strategy
• The PR description notes risks associated with the change, if any
• Newly-added code is easy to change
• The change follows the library release note guidelines
• The change includes or references documentation updates if necessary
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• Reviewer has checked that all the criteria below are met
• Title is accurate
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• Avoids breaking API changes
• Testing strategy adequately addresses listed risks
• Newly-added code is easy to change
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[github-actions]

CODEOWNERS have been resolved as:

tests/contrib/gunicorn/test_gunicorn.py                                 @DataDog/apm-core-python @DataDog/apm-idm-python

[pr-commenter]

Benchmarks

Benchmark execution time: 2024-11-13 15:39:21

Comparing candidate commit 2aa780f in PR branch wantsui/fix-gunicorn-flaky-test with baseline commit 48e8952 in branch main.

Found 1 performance improvements and 1 performance regressions! Performance is the same for 386 metrics, 2 unstable metrics.

scenario:iast_aspects-ljust_aspect

• 🟥 execution_time [+1.162µs; +1.274µs] or [+8.416%; +9.225%]

scenario:iast_aspects-ospathnormcase_aspect

• 🟩 execution_time [-256.024ns; -220.915ns] or [-9.571%; -8.258%]