Stop checking the change number capability.

It's been out for a year, no need to check at this point.

app/src/main/java/org/thoughtcrime/securesms/recipients/Recipient.java

@@ -1008,10 +1008,6 @@ public class Recipient {
     return forceSmsSelection;
   }
 
-  public @NonNull Capability getChangeNumberCapability() {
-    return capabilities.getChangeNumberCapability();
-  }
-
   public @NonNull Capability getStoriesCapability() {
     return capabilities.getStoriesCapability();
   }