Fix startup failures: drop permissions reusable-workflow callers cannot grant (#49055)
Drop permissions reusable-workflow callers cannot grant
#49046 added `pull-requests: read` to get-pr-info.yml and `actions: read`
to slack-report.yml. Both are reusable workflows, capped by their callers,
which only grant `contents: read`, so every calling run now fails at
startup. Both jobs ran fine with `contents: read` before #49046.
Co-authored-by: Claude Opus 5.5 (1M context) <noreply@anthropic.com>