extract: Plug huge leak
extract: Plug huge leak

Every GDBusMethodInvocation in handle_method_get_metadata_fast() was
being leaked, since that function is handling the replies itself.

hoheinzollern/tracker,hoheinzollern/tracker,hoheinzollern/tracker,outofbits/tracker,outofbits/tracker,outofbits/tracker,hoheinzollern/tracker,hoheinzollern/tracker,outofbits/tracker,outofbits/tracker,outofbits/tracker,outofbits/tracker,hoheinzollern/tracker,hoheinzollern/tracker