L2SS-451: Ignore submodule files in pipeline

.gitlab-ci.yml

bin/dump_ConfigDb.sh

bin/itango_console.sh

bin/itango_shell.sh

bin/start-DS.sh

bootstrap/etc/lofar20rc.sh

devices/integration_test/devices/test_device_recv.py

devices/integration_test/devices/test_device_sdp.py

devices/integration_test/devices/test_tango_database.py

docker-compose/archiver.yml

docker-compose/device-apsct.yml

docker-compose/device-apspu.yml

docker-compose/device-boot.yml

docker-compose/device-docker.yml

docker-compose/device-observation_control.yml

docker-compose/device-recv.yml

docker-compose/device-sdp.yml

docker-compose/device-sst.yml

docker-compose/device-unb2.yml

docker-compose/device-xst.yml