Ensure the group shortstring in the action bar is up-to-date.

There were situations where adding/removing members from a group
would update the group member list, but the short string (the little
text listing the first couple members of the group) wouldn't be updated
until you left the screen and came back.

src/org/thoughtcrime/securesms/database/GroupDatabase.java

@@ -248,6 +248,10 @@ public class GroupDatabase extends Database {
 
     databaseHelper.getWritableDatabase().update(TABLE_NAME, contents, GROUP_ID + " = ?",
                                                 new String[] {groupId});
+
+    Recipient.applyCached(Address.fromSerialized(groupId), recipient -> {
+      recipient.setParticipants(Stream.of(members).map(a -> Recipient.from(context, a, false)).toList());
+    });
   }
 
   public void remove(String groupId, Address source) {
@@ -259,6 +263,14 @@ public class GroupDatabase extends Database {
 
     databaseHelper.getWritableDatabase().update(TABLE_NAME, contents, GROUP_ID + " = ?",
                                                 new String[] {groupId});
+
+    Recipient.applyCached(Address.fromSerialized(groupId), recipient -> {
+      List<Recipient> current = recipient.getParticipants();
+      Recipient       removal = Recipient.from(context, source, false);
+
+      current.remove(removal);
+      recipient.setParticipants(current);
+    });
   }
 
   private List<Address> getCurrentMembers(String groupId) {