Optimize CI

[krystofwoldrich]

Description

Summary of CI improvements we can do to our current CI.

### Improvements
- [ ] Cache the plain E2E app builds before adding Sentry
- [ ] Create Job dependencies, only build the SDK once
- [ ] Improve e2e measurements of app start time
- [ ] Do not ran ci for changelog changes
- [x] Use Linux runners for Android e2e app builds

[kahest]

about Linux runners, maybe useful for Android runs: https://github.com/getsentry/sentry-java/pull/3071/files#diff-fc6c05b53998713db6ac269f92471cf26730b2cf242c2460ff908b0799d9b303