ci: use ubuntu-latest for functional tests. Improve CI caching

[wzieba]

Description

This PR:

• moves running functional tests from macOS to Ubuntu runner as KVM is now enabled on Ubuntu. The improvement is significant - from ~13m to ~5m per run
• delegates caching to gradle-build-action
• send dependencies on each push because it helps in tracking closed security alerts
• caches AVD files

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Comparison is base (761cf77) 57.60% compared to head (230ce39) 57.60%.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #107 +/- ## ======================================= Coverage 57.60% 57.60% ======================================= Files 19 19 Lines 401 401 Branches 48 48 ======================================= Hits 231 231 Misses 157 157 Partials 13 13 ```

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[wzieba]

Merging without review, as this PR contains only CI changes. I'm fairly confident with them. They don't affect the production code.