cogl/tests: Use less verbose run-tests.sh on single tests run by meson

Use less verbose output when run-tests.sh is running only a test and we're
requested for less verbose output.

GNOME/mutter!442
3 jobs for !442 with meson-test-suites in 5 minutes and 54 seconds (queued for 1 second)
detached
Status Job ID Name Coverage
  Review
passed #263837
check-commit-log

00:00:58

 
  Build
passed #263838
build-mutter

00:01:34

 
  Test
passed #263839
test-mutter

00:03:20