chore(sampling): add rc for trace sampling rules

[ZStriker19]

This PR implements remote config for DD_TRACE_SAMPLING_RULES:

1. Add the rc
2. Add provenance which we parse from rc and use to give a new decision maker _dd.p.dm to either -11 for customer configuration or -12 for dynamic configuration.
3. The most confusing part of this implementation takes place in tracer._on_global_config_update. Essentially implementing the logic for choosing the correct sample_rate and sampling_rules depending on rc input.

In addition to the sample_rate we already had I added one for sampling_rules and for the interaction between them. This PR also passes the newly added system-tests for this behavior.

Since this feature is in internal beta, there's no release note.

Checklist

• Change(s) are motivated and described in the PR description
• Testing strategy is described if automated tests are not included in the PR
• Risks are described (performance impact, potential for breakage, maintainability)
• Change is maintainable (easy to change, telemetry, documentation)
• Library release note guidelines are followed or label changelog/no-changelog is set
• Documentation is included (in-code, generated user docs, public corp docs)
• Backport labels are set (if applicable)
• If this PR changes the public interface, I've notified @DataDog/apm-tees.

Reviewer Checklist

• Title is accurate
• All changes are related to the pull request's stated goal
• Description motivates each change
• Avoids breaking API changes
• Testing strategy adequately addresses listed risks
• Change is maintainable (easy to change, telemetry, documentation)
• Release note makes sense to a user of the library
• Author has acknowledged and discussed the performance implications of this PR as reported in the benchmarks PR comment
• Backport labels are set in a manner that is consistent with the release branch maintenance policy

[datadog-dd-trace-py-rkomorn]

Datadog Report

Branch report: zachg/add_rcm_for_trace_sampling_rules
Commit report: 8d2f553
Test service: dd-trace-py

✅ 0 Failed, 131616 Passed, 42229 Skipped, 6h 2m 38.51s Total duration (4h 20m 5.62s time saved)
⌛ 1 Performance Regression

⌛ Performance Regressions vs Default Branch (1)

• test_data_streams_default_context_propagation - test_kafka.py 1m 30s (+1m 26.03s, +2169%) - Details

[pr-commenter]

Benchmarks

Benchmark execution time: 2024-04-30 18:42:23

Comparing candidate commit 3fc5773 in PR branch zachg/add_rcm_for_trace_sampling_rules with baseline commit 815da75 in branch main.

Found 9 performance improvements and 10 performance regressions! Performance is the same for 182 metrics, 9 unstable metrics.

scenario:flasksimple-appsec-get

• 🟥 execution_time [+198.033µs; +252.738µs] or [+3.151%; +4.021%]

scenario:httppropagationextract-full_t_id_datadog_headers

• 🟩 max_rss_usage [-691.475KB; -435.334KB] or [-3.242%; -2.041%]

scenario:httppropagationextract-invalid_trace_id_header

• 🟩 max_rss_usage [-900.591KB; -550.622KB] or [-4.262%; -2.606%]

scenario:httppropagationextract-valid_headers_all

• 🟥 max_rss_usage [+595.031KB; +746.818KB] or [+2.883%; +3.618%]

scenario:httppropagationextract-wsgi_large_header_no_matches

• 🟥 max_rss_usage [+572.634KB; +665.586KB] or [+2.767%; +3.216%]

scenario:httppropagationextract-wsgi_medium_header_no_matches

• 🟥 max_rss_usage [+555.333KB; +643.567KB] or [+2.685%; +3.112%]

scenario:httppropagationextract-wsgi_valid_headers_basic

• 🟩 max_rss_usage [-708.177KB; -635.720KB] or [-3.329%; -2.988%]

scenario:sethttpmeta-all-disabled

• 🟩 max_rss_usage [-711.392KB; -622.675KB] or [-3.293%; -2.882%]

scenario:sethttpmeta-all-enabled

• 🟩 max_rss_usage [-731.033KB; -655.872KB] or [-3.382%; -3.035%]

scenario:sethttpmeta-obfuscation-disabled

• 🟥 max_rss_usage [+938.437KB; +1025.186KB] or [+4.528%; +4.946%]

scenario:sethttpmeta-obfuscation-regular-case-explicit-query

• 🟥 max_rss_usage [+578.359KB; +653.308KB] or [+2.724%; +3.077%]

scenario:sethttpmeta-obfuscation-regular-case-implicit-query

• 🟥 max_rss_usage [+942.299KB; +1018.866KB] or [+4.510%; +4.877%]

scenario:sethttpmeta-useragentvariant_exists_1

• 🟩 max_rss_usage [-652.133KB; -580.353KB] or [-3.020%; -2.688%]

scenario:sethttpmeta-useragentvariant_exists_2

• 🟩 max_rss_usage [-709.397KB; -628.766KB] or [-3.284%; -2.911%]

scenario:sethttpmeta-useragentvariant_exists_3

• 🟩 max_rss_usage [-715.716KB; -637.193KB] or [-3.314%; -2.951%]

scenario:sethttpmeta-useragentvariant_not_exists_1

• 🟥 max_rss_usage [+729.781KB; +807.857KB] or [+3.498%; +3.872%]

scenario:span-start-finish

• 🟩 max_rss_usage [-718.886KB; -639.757KB] or [-3.370%; -2.999%]

scenario:tracer-large

• 🟥 max_rss_usage [+703.732KB; +791.308KB] or [+3.238%; +3.641%]

scenario:tracer-small

• 🟥 max_rss_usage [+744.536KB; +828.328KB] or [+3.613%; +4.020%]

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 9.70874% with 93 lines in your changes are missing coverage. Please review.

Project coverage is 6.58%. Comparing base (815da75) to head (fa806ca).
Report is 1 commits behind head on main.

Files	Patch %	Lines
ddtrace/settings/config.py	0.00%	26 Missing ⚠️
ddtrace/_trace/tracer.py	8.69%	21 Missing ⚠️
ddtrace/sampler.py	6.66%	14 Missing ⚠️
tests/internal/test_settings.py	0.00%	11 Missing ⚠️
tests/internal/remoteconfig/test_remoteconfig.py	0.00%	10 Missing ⚠️
ddtrace/internal/sampling.py	33.33%	6 Missing ⚠️
ddtrace/internal/constants.py	0.00%	3 Missing ⚠️
ddtrace/sampling_rule.py	0.00%	2 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##             main    #8900       +/-   ##
===========================================
- Coverage   68.03%    6.58%   -61.45%     
===========================================
  Files        1266     1236       -30     
  Lines      119540   117846     -1694     
===========================================
- Hits        81328     7762    -73566     
- Misses      38212   110084    +71872     

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