Remove collapse_key from android fcm request

flutter/TODO.md

@@ -37,3 +37,4 @@
  - [ ] Disable compat | remove code 
         - [x] compat message title
         - [ ] ...
+ - [ ] RWLock directly in go - prevent/reduce db-locked exception

scnserver/push/firebase.go

@@ -68,7 +68,6 @@ func (fb FirebaseConnector) SendNotification(ctx context.Context, user models.Us
 	} else if client.Type == models.ClientTypeAndroid {
 		jsonBody["android"] = gin.H{
 			"priority": "high",
-			"collapse_key": msg.ChannelID.String(),
 			"notification": gin.H{
 				"event_time": msg.Timestamp().Format(time.RFC3339),
 				"title":      msg.FormatNotificationTitle(user, channel),