MediaLibrary: Remove hook on Playlist::MediaRelationTable

Those would cause the relation table rowid to be used, which is of no
use to the application as the table is not publicly accessible

src/MediaLibrary.cpp

@@ -557,10 +557,6 @@ void MediaLibrary::registerEntityHooks()
         else if ( reason == sqlite::Connection::HookReason::Update )
             m_modificationNotifier->notifyPlaylistModification( rowId );
     });
-    m_dbConnection->registerUpdateHook( Playlist::MediaRelationTable::Name,
-                                        [this]( sqlite::Connection::HookReason, int64_t rowId ) {
-        m_modificationNotifier->notifyPlaylistModification( rowId );
-    });
     m_dbConnection->registerUpdateHook( Genre::Table::Name,
                                         [this]( sqlite::Connection::HookReason reason, int64_t rowId ) {
         if ( reason == sqlite::Connection::HookReason::Delete )