Build sample app against AGP matrix on CI

[romtsn]

Description

Similar to https://github.com/getsentry/sentry-android-gradle-plugin/blob/1deb7a6da144fdf6e55c86634afa9387132ec80c/.github/workflows/test-publish-dry-run.yaml#L15-L40

This would help catch regressions with preview versions of AGP, similar to this one getsentry/sentry-android-gradle-plugin#321 (comment)

[adinauer]

We want to do this for the android sample.