Add kcov merge task in the pipeline
Related with https://gitlab.com/cki-project/kpet-db/-/issues/53
Can't be merge until containers!332 (merged) will be merged.
We're extracted the logic from https://gitlab.com/cki-project/kernel-tests/-/blob/main/kcov/merge/runtest.sh,
This part of the pipeline is only executed when coverage is enabled.
Edited by Israel Santana Aleman