Relax some shellcheck tests and fix remaining issues

3 jobs for tests in 1 minute and 7 seconds (queued for 1 second)
Status Job ID Name Coverage
  Test
passed #39456
dockerfiles

00:00:45

passed #39455
shellcheck

00:00:43

failed #39457
allowed to fail
yamllint

00:00:24

 
Name Stage Failure
failed
yamllint Test
No job log