Make sure we do not drift on accounting.

Three issues were found and resolved.

1. Purge replays after recovery could execute full purge.
2. Callback was registered without lock, which could lead to skew.
3. Cluster reset could stop stream store and recreate it, which could lead to double accounting.

Signed-off-by: Derek Collison <derek@nats.io>

server/jetstream_api.go

@@ -1,4 +1,4 @@
-// Copyright 2020-2022 The NATS Authors
+// Copyright 2020-2023 The NATS Authors
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.
 // You may obtain a copy of the License at
@@ -2656,7 +2656,7 @@ func (s *Server) jsLeaderAccountPurgeRequest(sub *subscription, c *client, _ *Ac
 }
 
 // Request to have the meta leader stepdown.
-// These will only be received the meta leaders, so less checking needed.
+// These will only be received by the meta leader, so less checking needed.
 func (s *Server) jsLeaderStepDownRequest(sub *subscription, c *client, _ *Account, subject, reply string, rmsg []byte) {
 	if c == nil || !s.JetStreamEnabled() {
 		return