tests: Move qdict-test-data.txt to tests/data/qobject/

Move qdict-test-data.txt to the tests/data/qobject/ subdirectory,
and remove the unnecessary symlinking.
(See 4b2ff65a for similar test-data cleanup).

Suggested-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Reviewed-by: Markus Armbruster <armbru@redhat.com>
[thuth: Fix conflict in MAINTAINERS]
Signed-off-by: Thomas Huth <thuth@redhat.com>