Some tests expect warnings to be logged, and handle that using
g_test_expect_message(). However, if debug topics are enabled, this
causes g_logv() to expect expected messages to also contain entries with
the debug level 'message' or higher to be listed in the expected message
list. Since meta_topic() always logged using g_message(), enabling debug
topics caused any test that used g_test_expect_message() and had debug
logging somewhere along the code path to fail.
Fix this by changing the log level of meta_topic() to 'debug' if we're
in a test. This doesn't mean they won't be visible, they still will
since debug log entries are printed by default during testing.
Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/2800>
11d35f99be