chore(protocol): only allow enc. password changes on cluster config (#10145)

In practice we already always call SetPassword and ClusterConfig
together. However it's not just "sensible" to do that, it's required: If
the passwords change, the remote device needs to know about that to
check that the enc. setup is valid/consistent (e.g. tokens match,
folder-type is appropriate, ...).
And with the passwords set later, there's no point in adding them as
part of creating a new connection.

This is a "followup" (if one can call it that 4 years later :) ) to
resp. fix for the following commit:
924b96856f

Co-authored-by: Jakob Borg <jakob@kastelo.net>

lib/model/model.go

@@ -1629,8 +1629,7 @@ func (m *model) sendClusterConfig(ids []protocol.DeviceID) {
 	// Generating cluster-configs acquires the mutex.
 	for _, conn := range ccConns {
 		cm, passwords := m.generateClusterConfig(conn.DeviceID())
-		conn.SetFolderPasswords(passwords)
-		go conn.ClusterConfig(cm)
+		go conn.ClusterConfig(cm, passwords)
 	}
 }
 
@@ -2406,10 +2405,9 @@ func (m *model) promoteConnections() {
 			l.Debugf("Promoting connection to %s at %s", deviceID.Short(), conn)
 			postLockActions = append(postLockActions, func() {
 				if conn.Statistics().StartedAt.IsZero() {
-					conn.SetFolderPasswords(passwords)
 					conn.Start()
 				}
-				conn.ClusterConfig(cm)
+				conn.ClusterConfig(cm, passwords)
 			})
 			m.promotedConnID[deviceID] = connIDs[0]
 		}
@@ -2420,9 +2418,8 @@ func (m *model) promoteConnections() {
 			conn := m.connections[connID]
 			if conn.Statistics().StartedAt.IsZero() {
 				postLockActions = append(postLockActions, func() {
-					conn.SetFolderPasswords(passwords)
 					conn.Start()
-					conn.ClusterConfig(&protocol.ClusterConfig{Secondary: true})
+					conn.ClusterConfig(&protocol.ClusterConfig{Secondary: true}, passwords)
 				})
 			}
 		}