delete unneeded lines in .gitlab-ci.yml

3 jobs for adi-dev in 12 seconds
Name Stage Failure
failed
EMAM2CppBuild Build
$ git clone git@github.com:MontiCore/EmbeddedMontiArc.git
Cloning into 'EmbeddedMontiArc'...
Host key verification failed.
fatal: Could not read from remote repository.

Please make sure you have the correct access rights
and the repository exists.
Cleaning up file based variables
ERROR: Job failed: exit code 1