Update the apertis-image-recipes repo to use one gitlab job per Lava job

This matches the changes to the apertis-test-cases repo. Previously we had a two stage process for Lava tests of:

• generate and submit
• monitor

for each set of test cases. This is a restrictive setup, because it is impossible to use CI_JOB_TOKEN within the lava jobs themselves (because the token expires on completion of the submission job, before the lava job itself may even have started).

The new model is simply:

• generate tests and pipeline
• Run each test in its own job in the generated pipeline

That means we still have pairs of jobs at the top level, one job to generate the tests, as before, which now also generates a pipeline; the second job is a trigger job which executes the pipeline, bringing in the generated tests.

This is draft until apertis-test-cases!472 is merged.

https://phabricator.apertis.org/T8952