chore(asm): don't load appsec modules (iast) if disabled

[christophe-papazian]

The goal is to make sure no appsec module is loaded if appsec is disabled.
This PR is the first one of 2, handling IAST.
It removes all non guarded IAST import from outside appsec.

• ensure we don't load any iast module if iast is disabled
• replace _is_iast_enabled() by a field _iast_enabled in the asm config

APPSEC-56626

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:

ddtrace/_monkey.py                                                      @DataDog/apm-core-python
ddtrace/appsec/_asm_request_context.py                                  @DataDog/asm-python
ddtrace/appsec/_iast/__init__.py                                        @DataDog/asm-python
ddtrace/appsec/_iast/_handlers.py                                       @DataDog/asm-python
ddtrace/appsec/_iast/_iast_request_context.py                           @DataDog/asm-python
ddtrace/appsec/_iast/_loader.py                                         @DataDog/asm-python
ddtrace/appsec/_iast/_pytest_plugin.py                                  @DataDog/asm-python
ddtrace/appsec/_iast/_utils.py                                          @DataDog/asm-python
ddtrace/appsec/_iast/taint_sinks/insecure_cookie.py                     @DataDog/asm-python
ddtrace/contrib/dbapi/__init__.py                                       @DataDog/apm-core-python @DataDog/apm-idm-python
ddtrace/contrib/dbapi_async/__init__.py                                 @DataDog/apm-core-python @DataDog/apm-idm-python
ddtrace/contrib/internal/fastapi/patch.py                               @DataDog/apm-core-python @DataDog/apm-idm-python
ddtrace/contrib/internal/langchain/patch.py                             @DataDog/ml-observability
ddtrace/contrib/internal/pytest/plugin.py                               @DataDog/apm-core-python @DataDog/apm-idm-python
ddtrace/contrib/internal/starlette/patch.py                             @DataDog/apm-core-python @DataDog/apm-idm-python
ddtrace/internal/iast/product.py                                        @DataDog/asm-python
ddtrace/settings/asm.py                                                 @DataDog/asm-python
tests/appsec/iast/fixtures/integration/main_configure.py                @DataDog/asm-python
tests/appsec/integrations/django_tests/test_django_appsec_iast.py       @DataDog/asm-python
tests/appsec/integrations/flask_tests/test_iast_flask.py                @DataDog/asm-python
tests/contrib/dbapi/test_dbapi_appsec.py                                @DataDog/asm-python

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 18.75000% with 39 lines in your changes missing coverage. Please review.

Please upload report for BASE (3.x-staging@0ed084a). Learn more about missing BASE report.

Files with missing lines	Patch %	Lines
ddtrace/appsec/_iast/_handlers.py	0.00%	17 Missing ⚠️
ddtrace/appsec/_iast/_pytest_plugin.py	0.00%	3 Missing ⚠️
ddtrace/contrib/internal/langchain/patch.py	0.00%	3 Missing ⚠️
ddtrace/appsec/_iast/_iast_request_context.py	50.00%	2 Missing ⚠️
ddtrace/appsec/_iast/_loader.py	0.00%	2 Missing ⚠️
...dtrace/appsec/_iast/taint_sinks/insecure_cookie.py	0.00%	2 Missing ⚠️
ddtrace/contrib/dbapi_async/__init__.py	50.00%	2 Missing ⚠️
ddtrace/contrib/internal/pytest/plugin.py	0.00%	2 Missing ⚠️
ddtrace/settings/asm.py	33.33%	2 Missing ⚠️
ddtrace/_monkey.py	50.00%	1 Missing ⚠️
... and 3 more

Additional details and impacted files

@@              Coverage Diff               @@
##             3.x-staging   #12184   +/-   ##
==============================================
  Coverage               ?   12.74%           
==============================================
  Files                  ?     1606           
  Lines                  ?   135677           
  Branches               ?        0           
==============================================
  Hits                   ?    17298           
  Misses                 ?   118379           
  Partials               ?        0           

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[datadog-dd-trace-py-rkomorn]

Datadog Report

Branch report: christophe-papazian/remove_appsec_dependencies_if_serverless
Commit report: 484dae9
Test service: dd-trace-py

✅ 0 Failed, 130 Passed, 1468 Skipped, 4m 41.04s Total duration (35m 44.47s time saved)

[pr-commenter]

Benchmarks

Benchmark execution time: 2025-02-03 14:47:27

Comparing candidate commit 484dae9 in PR branch christophe-papazian/remove_appsec_dependencies_if_serverless with baseline commit a22143d in branch 3.x-staging.

Found 0 performance improvements and 0 performance regressions! Performance is the same for 394 metrics, 2 unstable metrics.