Clean unneeded refs to metricDB

.. starting to sunset the code now. Need to sort the sqlModel
   for the ridecache and then it can be retired completely.

src/LTMWindow.cpp

@@ -658,7 +658,7 @@ LTMWindow::filterChanged()
     // ignore in compare mode
     if (isCompare()) return;
 
-    if (amVisible() == false || context->athlete->metricDB == NULL) return;
+    if (amVisible() == false) return;
 
     if (useCustom) {
 

src/RideMetadata.cpp

@@ -1070,8 +1070,7 @@ RideMetadata::readXML(QString filename, QList<KeywordDefinition>&keywordDefiniti
 
     // now auto append special fields, in case
     // the user wiped them or we have introduced
-    // them in this release. This is to ensure
-    // they get written to metricDB
+    // them in this release.
     bool hasCalendarText = false;
     bool hasData = false;