Pontoon: Update German (de) localization of Firefox Screenshots

Localization authors:
- Michael Köhler <michael.koehler1@gmx.de>

locales/de/server.ftl

@@ -314,13 +314,11 @@ shotIndexPagePreviousPage =
     .title = Vorherige Seite
 shotIndexPageNextPage =
     .title = Nächste Seite
-# This symbol is used in the lower right corner of the card for a shot on the
-# My Shots page to indicate that the shot does not expire. It should be a
-# single character (or simply nothing if no such symbol is available for a
-# language/culture).
-shotIndexNoExpirationSymbol = ∞
-    .title = Dieses Bildschirmfoto läuft nicht ab
-# This is the tooltip for a "heart" symbol in the lower right corner of the
+# This is tooltip for a "blank heart" symbol used in the upper top corner of the card for a shot on the
+# My Shots page to indicate that the shot does expire.
+shotIndexNonFavoriteIcon =
+    .title = Dieses Bildschirmfoto ist kein Favorit, daher läuft es ab
+# This is the tooltip for a "heart" symbol in the upper top corner of the
 # card for a shot on the My Shots page. It indicate that the shot was marked as
 # a favorite by the owner.
 shotIndexFavoriteIcon =