[chore] Update check-links workflow to match contrib logic

[TylerHelmuth]

Description:
Quick PR to closer align Core's checklink workflow with Contribs. I am hoping it fixes issues like this: https://github.com/open-telemetry/opentelemetry-collector/runs/7452564621?check_suite_focus=true.

[codecov]

Codecov Report

Merging #5728 (9740a16) into main (61c6989) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##             main    #5728   +/-   ##
=======================================
  Coverage   91.56%   91.56%           
=======================================
  Files         192      192           
  Lines       11411    11411           
=======================================
  Hits        10449    10449           
  Misses        768      768           
  Partials      194      194           

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[bogdandrutu]

Description:
Quick PR to closer align Core's checklink workflow with Contribs. I am hoping it fixes issues like this: https://github.com/open-telemetry/opentelemetry-collector/runs/7452564621?check_suite_focus=true.

[just for me to understand the logic]: Can you please explain how? That to me looks like a problem in the tool.

[TylerHelmuth]

That to me looks like a problem in the tool.

I don't think so. In the build I linked the check-links job fails because there is a bad link in docs/release.md. The command being run is exactly

markdown-link-check \
    --verbose \
    --config .github/workflows/check_links_config.json \
    CHANGELOG.md docs/release.md

So the job is correctly running against the 2 files it was told to and finding a bad link in one of them. The problem is that my branch did not modify the docs/release.md file, so it shouldn't get passed to markdown-link-check.

In the "changed files" job the runs before the check-links job, the git diff command that checks what files changes is git diff --name-only --diff-filter=ACMRTUXB origin/main f34584b43df46ad8afa134184311cd45ec07bd31 | grep .md$ | xargs. When I run that locally I get CHANGELOG.md and docs/release.md.

If I run this PR's version of the git diff command for that PR instead, it only returns CHANGELOG.md, which is correct.

[TylerHelmuth]

@djaglowski is the git wizard who fixed this issue in Contrib. Comparing against the common ancestor using git merge-base instead of directly against main is the key.