tdf#129210 don't assert with clear on already cleared mutex

reset it after load completes, seeing as the comment suggests
that's why the clear exists in the first place

Change-Id: I3af633c5a1f99b5d0dd754c21e220c6c94b66634
Reviewed-on: https://gerrit.libreoffice.org/84778
Reviewed-by: Mike Kaganski <mike.kaganski@collabora.com>
Tested-by: Xisco Faulí <xiscofauli@libreoffice.org>
Tested-by: Jenkins
Reviewed-by: Caolán McNamara <caolanm@redhat.com>
Tested-by: Caolán McNamara <caolanm@redhat.com>

dbaccess/source/core/dataaccess/databasedocument.cxx

@@ -685,6 +685,7 @@ void SAL_CALL ODatabaseDocument::recoverFromFile( const OUString& i_SourceLocati
 
         aGuard.clear(); // (load has an own guarding scheme)
         load( aMediaDescriptor.getPropertyValues() );
+        aGuard.reset();
 
         // Without a controller, we are unable to recover the sub components, as they're always tied to a controller.
         // So, everything else is done when the first controller is connected.