Replace go-migrate with morph (#19116)

store/retrylayer/retrylayer.go

@@ -2023,27 +2023,6 @@ func (s *RetryLayerChannelStore) MigrateChannelMembers(fromChannelID string, fro
 
 }
 
-func (s *RetryLayerChannelStore) MigratePublicChannels() error {
-
-	tries := 0
-	for {
-		err := s.ChannelStore.MigratePublicChannels()
-		if err == nil {
-			return nil
-		}
-		if !isRepeatableError(err) {
-			return err
-		}
-		tries++
-		if tries >= 3 {
-			err = errors.Wrap(err, "giving up after 3 consecutive repeatable transaction failures")
-			return err
-		}
-		timepkg.Sleep(100 * timepkg.Millisecond)
-	}
-
-}
-
 func (s *RetryLayerChannelStore) PermanentDelete(channelID string) error {
 
 	tries := 0