libtracker-data: remove all null checks before g_free() in db-manager
libtracker-data: remove all null checks before g_free() in db-manager

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