fix(iast): avoid native module import if iast disabled

[gnufede]

IAST: Forces an ImportError if the IAST _taint_tracking native module is imported when IAST is not enabled, to ensure there are no side_effects, like segmentation faults, if IAST is not enabled.

Fixes #8504

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.
• If change touches code that signs or publishes builds or packages, or handles credentials of any kind, I've requested a review from @DataDog/security-design-and-guidance.

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: gnufede/avoid-native-load-if-iast-disabled
Commit report: 530e975
Test service: dd-trace-py

✅ 0 Failed, 129632 Passed, 42335 Skipped, 7h 45m 0s Total duration (3h 55m 5.53s time saved)

[pr-commenter]

Benchmarks

Benchmark execution time: 2024-03-04 18:58:08

Comparing candidate commit ba4841a in PR branch gnufede/avoid-native-load-if-iast-disabled with baseline commit 6592d5d in branch main.

Found 0 performance improvements and 7 performance regressions! Performance is the same for 194 metrics, 9 unstable metrics.

scenario:coreapiscenario-context_with_data_only_all_listeners

• 🟥 max_rss_usage [+642.919KB; +788.633KB] or [+2.199%; +2.698%]

scenario:coreapiscenario-core_dispatch_with_results_listeners

• 🟥 max_rss_usage [+729.877KB; +865.105KB] or [+2.499%; +2.962%]

scenario:httppropagationinject-with_tags

• 🟥 max_rss_usage [+672.818KB; +755.457KB] or [+2.300%; +2.583%]

scenario:otelspan-start-finish

• 🟥 max_rss_usage [+681.333KB; +831.320KB] or [+2.224%; +2.714%]

scenario:otelspan-start-finish-telemetry

• 🟥 max_rss_usage [+681.722KB; +800.621KB] or [+2.224%; +2.612%]

scenario:sethttpmeta-obfuscation-send-querystring-disabled

• 🟥 max_rss_usage [+692.781KB; +806.764KB] or [+2.321%; +2.703%]

scenario:span-add-metrics

• 🟥 max_rss_usage [+25.777MB; +25.878MB] or [+65.934%; +66.192%]

[github-actions]

The backport to 2.4 failed:

The process '/usr/bin/git' failed with exit code 1

To backport manually, run these commands in your terminal:

# Fetch latest updates from GitHub
git fetch
# Create a new working tree
git worktree add .worktrees/backport-2.4 2.4
# Navigate to the new working tree
cd .worktrees/backport-2.4
# Create a new branch
git switch --create backport-8564-to-2.4
# Cherry-pick the merged commit of this pull request and resolve the conflicts
git cherry-pick -x --mainline 1 b4a1d979c7b85b91b9a31e0a763a043c74f97d78
# Push it to GitHub
git push --set-upstream origin backport-8564-to-2.4
# Go back to the original working tree
cd ../..
# Delete the working tree
git worktree remove .worktrees/backport-2.4

Then, create a pull request where the base branch is 2.4 and the compare/head branch is backport-8564-to-2.4.

[github-actions]

The backport to 2.5 failed:

The process '/usr/bin/git' failed with exit code 1

To backport manually, run these commands in your terminal:

# Fetch latest updates from GitHub
git fetch
# Create a new working tree
git worktree add .worktrees/backport-2.5 2.5
# Navigate to the new working tree
cd .worktrees/backport-2.5
# Create a new branch
git switch --create backport-8564-to-2.5
# Cherry-pick the merged commit of this pull request and resolve the conflicts
git cherry-pick -x --mainline 1 b4a1d979c7b85b91b9a31e0a763a043c74f97d78
# Push it to GitHub
git push --set-upstream origin backport-8564-to-2.5
# Go back to the original working tree
cd ../..
# Delete the working tree
git worktree remove .worktrees/backport-2.5

Then, create a pull request where the base branch is 2.5 and the compare/head branch is backport-8564-to-2.5.