chore(ci_visibility): only store longrepr as XFAIL_REASON if the test is an xfail

[romainkomorndatadog]

This primarily addresses warning messages that would be shown if a test was marked as skipped by ITR, but also xfailed.

This would've resulted in a log warning that the test item was already finished, which would result in the tag setting being a noop.

No changelog is added because this plugin is not yet released.

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/contrib/pytest/_plugin_v2.py                                    @DataDog/ci-app-libraries

[pr-commenter]

Benchmarks

Benchmark execution time: 2024-08-26 13:49:30

Comparing candidate commit f0f45f7 in PR branch romain.komorn/SDTEST-225/dont_readd_tag_for_xfail_skips with baseline commit 262b9d6 in branch main.

Found 0 performance improvements and 0 performance regressions! Performance is the same for 353 metrics, 47 unstable metrics.