creator: disable debug level for the qtc.* logging categories

by default all subcategories of qtc have debugging disabled.
This allows to easily use them for verbose output and replace
per module/file debug flags.

Change-Id: I130c496a9ee83d3b3b5cbd9b4e087dc00c40b113
Reviewed-by: Kai Koehne <kai.koehne@digia.com>
Reviewed-by: Fawzi Mohamed <fawzi.mohamed@digia.com>