Fix GMD tests

[ArnyminerZ]

Purpose

Research and maybe fix #866

Short description

Checklist

• The PR has a proper title, description and label.
• I have self-reviewed the PR.
• I have added documentation to complex functions and functions that can be used by other modules.
• I have added reasonable tests or consciously decided to not add tests.

[ArnyminerZ]

I've tried all the options I can think of to see whether it is a cache issue since the task started failing randomly (https://github.com/bitfireAT/davx5-ose/actions/runs/9660381810) however nothing seems to work.

[ArnyminerZ]

Does run locally without any issues

[ArnyminerZ]

May be related to AGP since last merge to main-ose was in https://github.com/bitfireAT/davx5-ose/actions/runs/9537918257 before the first failing check

Edit: downgrading doesn't help

[ArnyminerZ]

Upgraded AGP again and restored to the original run command but cleared all caches from Github Actions

[rfc2822]

Runs with large runner; maybe really a resource problem? We could try to reduce required resources by reducing heap sizes etc, or just use the large runner (which doesn't have free minutes).

[rfc2822]

Seems this was caused by too little free space on the runner. I think because the gradle user cache become too big, because cleaning up the old entries is not very reliable. I tried to improve caching with a separate task and by excluding transformed JARs (>1 GB).