CI: Avoid unnecessary runner allocation by splitting platform matrix into separate jobs #5864
Description
Currently, native-tests.yml uses separate jobs per platform (ios-native-tests, android-native-tests) with job-level if conditions. This means when a platform is skipped, no runner is allocated at all. Other workflows like sample-application.yml and sample-application-expo.yml use platform as a matrix dimension alongside other axes (e.g. build-type, ios-use-frameworks). Skipping happens inside the job via a platform-check step, which means a runner is still allocated and torn down even when the platform is ultimately skipped.
We could adopt the native-tests.yml pattern in these workflows by splitting them into separate build-ios / build-android / build-web jobs, each with:
- A job-level if using the appropriate needs_* output
- A reduced matrix containing only the remaining axes (e.g. build-type, ios-use-frameworks)
This would avoid allocating (and paying for) runners that immediately skip.