ci: python-test rename artifacts

The current python-test job creates and compresses python related
artifacts for use by future jobs. The artifacts are currently named
`mesa-python-test` which is somewhat misleading because they are not
needed for testing python scripts or libraries.

Rename the artifacts generated by the python-test job to be more
descriptive of their purpose.

Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/32340>
6 files changed