ci: Move specific driver testing to separate files in separate dirs.

ci: Move specific driver testing to separate files in separate dirs.

The top-level gitlab-ci.yml is big and unwieldy when one wants to work on
CI for a single driver.  Move the drivers to separate include files for
ease of finding all your driver's tests, and also to pave the way for work
on a single driver's CI to not retest all other drivers.

Reviewed-by: Andres Gomez <agomez@igalia.com>
Reviewed-by: Juan A. Suarez <jasuarez@igalia.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/9139>