remove unused strings

locales/en-US/strings.conf

 #The first line is used for comment
 #line doesn't start with '!' is also neglected
+#called by DataManager::GetSysString(), DataManager::GetDesc()
 #system
 !system 1 Normal Summon
 !system 2 Special Summon
@@ -291,7 +292,6 @@
 !system 1253 Current Spectators:
 !system 1254 Select Deck
 !system 1255 Ready!
-!system 1270 Card
 !system 1260 Master Rules
 !system 1261 Master Rules 2
 !system 1262 Master Rules 3
@@ -344,7 +344,6 @@
 !system 1325 Search:
 !system 1326 Effect
 !system 1327 Search
-!system 1328 Filter results
 !system 1329 Series：
 !system 1330 Deck:
 !system 1331 Extra: