feat(asm): standalone sca billing

[gnufede]

ASM: This PR introduces the "Standalone SCA billing" feature, that can be enabled by setting the following env vars to "true" or 1:

1. DD_APPSEC_SCA_ENABLED
2. DD_EXPERIMENTAL_APPSEC_STANDALONE_ENABLED

With them enabled, the service will opt out for APM features, thus being billed only for the SCA feature.

System-tests: DataDog/system-tests#3690

Checklist

• PR author has checked that all the criteria below are met
• The PR description includes an overview of the change
• 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
• Backport labels are set (if applicable)

Reviewer Checklist

• Reviewer has checked that all the criteria below are met
• Title is accurate
• All changes are related to the pull request's stated goal
• Avoids breaking API changes
• Testing strategy adequately addresses listed risks
• Newly-added code is easy to change
• Release note makes sense to a user of the library
• If necessary, 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

[github-actions]

CODEOWNERS have been resolved as:

releasenotes/notes/feat-standalone-sca-billing-925c84d69fe061ce.yaml    @DataDog/apm-python
ddtrace/_trace/tracer.py                                                @DataDog/apm-sdk-api-python
tests/appsec/appsec/test_asm_standalone.py                              @DataDog/asm-python
tests/tracer/test_propagation.py                                        @DataDog/apm-sdk-api-python
tests/tracer/test_tracer.py                                             @DataDog/apm-sdk-api-python

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 14.03%. Comparing base (b7ca2d6) to head (35bba54).
Report is 35 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #11655      +/-   ##
==========================================
- Coverage   14.05%   14.03%   -0.02%     
==========================================
  Files        1545     1547       +2     
  Lines      134562   134265     -297     
==========================================
- Hits        18907    18841      -66     
+ Misses     115655   115424     -231     

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[pr-commenter]

Benchmarks

Benchmark execution time: 2024-12-17 13:58:39

Comparing candidate commit 38910cc in PR branch gnufede/sca-standalone with baseline commit a4f0e38 in branch main.

Found 0 performance improvements and 0 performance regressions! Performance is the same for 384 metrics, 2 unstable metrics.