tests: correct name of `check_db` to `check_repo`
tests: correct name of `check_db` to `check_repo`

- this test is checking the package *repository*, not the database.

LLNL/spack,iulian787/spack,krafczyk/spack,LLNL/spack,LLNL/spack,iulian787/spack,LLNL/spack,iulian787/spack,mfherbst/spack,mfherbst/spack,krafczyk/spack,krafczyk/spack,krafczyk/spack,iulian787/spack,iulian787/spack,mfherbst/spack,mfherbst/spack,krafczyk/spack,mfherbst/spack,LLNL/spack