Increase default log verbosity in CI
This branch contains various tweaks to logging. Some messages are demoted from g_info() to g_debug(), and one (when we do a blocking sqlite3_wal_checkpoint_v2() call) is promoted to g_info().
It also enables TRACKER_VERBOSITY=1 while we run the test suite. This means we'll get more detailed logs for failed tests and in the meson-logs/testlog.txt artifact.
Fixes #136 (closed)