fix(ci_visibility): use git tag as branch name if no branch name available [backport 3.7]

[vitor-de-araujo]

Backport 88cbdc8 from #13468 to 3.7.

When called from a GitHub action triggered on a tag push (not a branch push), we would have no branch name available and make some requests to the backend with a null branch, causing a 400 to be returned. This PR changes it so that the tag name is used as the branch name in such circumstances.

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

(cherry picked from commit 88cbdc8)

[github-actions]

CODEOWNERS have been resolved as:

releasenotes/notes/ci_visibility-fix-use-git-tag-as-branch-971227009e6496a6.yaml  @DataDog/apm-python
tests/ci_visibility/test_git_data.py                                    @DataDog/ci-app-libraries
ddtrace/internal/ci_visibility/git_data.py                              @DataDog/ci-app-libraries

[github-actions]

Bootstrap import analysis

Comparison of import times between this PR and base.

Summary

The average import time from this PR is: 231 ± 2 ms.

The average import time from base is: 232 ± 2 ms.

The import time difference between this PR and base is: -1.61 ± 0.09 ms.

Import time breakdown

The following import paths have grown:

ddtrace.auto 0.015 ms (0.01%)

ddtrace 0.015 ms (0.01%)

ddtrace._monkey 0.015 ms (0.01%)

ddtrace.appsec._listeners 0.015 ms (0.01%)

ddtrace.appsec 0.015 ms (0.01%)

The following import paths have shrunk:

ddtrace.auto 1.979 ms (0.86%)

ddtrace.bootstrap.sitecustomize 1.284 ms (0.56%)

ddtrace.bootstrap.preload 1.284 ms (0.56%)

ddtrace.internal.products 1.284 ms (0.56%)

ddtrace.internal.remoteconfig.client 0.649 ms (0.28%)

ddtrace 0.695 ms (0.30%)

ddtrace._logger 0.028 ms (0.01%)

logging 0.028 ms (0.01%)

traceback 0.028 ms (0.01%)

contextlib 0.028 ms (0.01%)

[pr-commenter]

Benchmarks

Benchmark execution time: 2025-05-26 14:53:57

Comparing candidate commit 2e5021e in PR branch backport-13468-to-3.7 with baseline commit e25092f in branch 3.7.

Found 0 performance improvements and 3 performance regressions! Performance is the same for 481 metrics, 4 unstable metrics.

scenario:iast_aspects-replace_aspect

• 🟥 execution_time [+786.168ns; +902.838ns] or [+17.053%; +19.584%]

scenario:iast_aspects-rsplit_aspect

• 🟥 execution_time [+136.763ns; +177.366ns] or [+9.295%; +12.054%]

scenario:iast_aspects-split_aspect

• 🟥 execution_time [+150.929ns; +176.355ns] or [+10.384%; +12.133%]