[Bug] CI: releasebranch_8_3 failure for CentOS and OSGeo4W

[neteler]

Describe the bug

The today's backporting of some PRs shows that the CI is no longer working ok for releasebranch_8_3.

CentoOS:

Run source $CONDA_ACTIVATE
/__w/_temp/10995748-8704-4199-986d-c0989f5a33ab.sh: line 1: source: filename argument required
source: usage: source filename [arguments]
Error: Process completed with exit code 2.

OSGeo4W:

Fatal Python error: init_fs_encoding: failed to get the Python codec of the filesystem encoding
Python runtime state: core initialized
ModuleNotFoundError: No module named 'encodings'

Logs:

• CentOS: https://github.com/OSGeo/grass/actions/runs/8798695813/job/24146234239
• OSGeo4W: https://github.com/OSGeo/grass/actions/runs/8798695807/job/24146234192

Expected behavior
The CI jobs should complete.

Additional context

Probably some CI-related backports are missing?

[nilason]

I believe 8.3 is not ready for Python 3.12, which is a problem.

[nilason]

#3603 should probably also be backported.

[nilason]

Centos runner was removed on main with #3141.

[wenzeslaus]

Centos runner was removed on main with #3141.

Removed on main AND not working with other changes we want -> remove.