ci: Mark Unit Tests as required checks for PRs

[philipphofmann]

Description

Make passing unit tests a required check for merging PRs. Enabling this check must not block PRs for which the unit tests don't run such as #5867. We can use the same approach with dorny/path-filters action as we do on the main repo https://github.com/getsentry/sentry/blob/master/.github/workflows/backend.yml.

[linear]

COCOA-520 ci: Mark Unit Tests as required checks for PRs