[chore] move api-diff pipeline to ubuntu runner

[mowies]

Description

Move the api-diff workflow to the standard ubuntu-latest runner and adjust the OS dependent call to mktemp so that it works for both linux and macos.

Link to tracking issue

Fixes #7444

Testing

Tested on my fork:
https://github.com/mowies/opentelemetry-collector/actions/runs/13941800348/job/39019991437

Also tested this locally on MacOS.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 91.55%. Comparing base (12dd09f) to head (d6c074f).
Report is 17 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main   #12549   +/-   ##
=======================================
  Coverage   91.55%   91.55%           
=======================================
  Files         480      480           
  Lines       26391    26391           
=======================================
  Hits        24162    24162           
  Misses       1766     1766           
  Partials      463      463           

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.

[github-actions]

This PR was marked stale due to lack of activity. It will be closed in 14 days.

[mowies]

The workflow is failing in the PR because it still uses the version from main branch I believe. It works on my fork and locally on macOS

[mx-psi]

The workflow is failing in the PR because it still uses the version from main branch I believe. It works on my fork and locally on macOS

Any way to fix that before merging this PR?

[mowies]

I don't think so...