Use a matrix to deploy and cleanup apps

[nirinchev]

This is building on top of #663 by moving the deploy/cleanup steps to separate jobs. This shaves 45-60 seconds from the test jobs and those typically complete by the time the build-native job completes, so tests are ready to run in about a minute.

The reason why this works is twofold:

1. We can split the deploy-apps job because our tests do not rely on it. The test runner will import the apps if necessary, so in the event of a re-run of the failed job, the test runner will fail to find the apps and import them itself.
2. We can split the cleanup-apps job because re-running a failed job will also re-run its dependents. In the event of a re-run, the cleanup will still be executed with the run attempt, so it will delete apps created by the test runner.

[desistefanova]

Cluster names have to be renewed on every 12 h to prevent running tests on automatically deleted clusters. Samples for names are dart16AM, dart16PM, dart17AM.

[desistefanova]

Could we return back this step for generating different names on every 12 h?