fix(lib-injection): fix guardrail check when sys.argv is not available [backport 2.16]

[github-actions]

Backport 48e8952 from #11364 to 2.16.

Related to: DataDog/system-tests#3403

sys.argv is not always available: https://bugs.python.org/issue32573

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

[pr-commenter]

Benchmarks

Benchmark execution time: 2024-11-27 16:32:31

Comparing candidate commit 1f610aa in PR branch backport-11364-to-2.16 with baseline commit 1a21259 in branch 2.16.

Found 0 performance improvements and 0 performance regressions! Performance is the same for 388 metrics, 2 unstable metrics.

[github-actions]

CODEOWNERS have been resolved as:

releasenotes/notes/fix-lib-injection-sys-argv-fefc775a4a262d86.yaml     @DataDog/apm-python
lib-injection/sources/sitecustomize.py                                  @DataDog/apm-core-python