As a Release Manager I can tag builds not the deleted from CI storage

For certain Qt builds, like final releases, it is important that they are not cleaned from the CI storage in any circumstances.

This is because these builds are used by other product and if they don’t exist they will be rebuild.

Both build results and the virtual machine images used to build them need to be retained.

The ideas is to locks two latest patch releases from each Qt major branch, like 5.12.5, 5.12.6, 5.13.1, 5.13.2….

Acceptance criteria:

 * a way (can be for example Web UI) to modify the rules which builds need to be retained

 * COIN storage cleanup tasks follow the rules

 * unit tests