MM-25700 : Use a counting semaphore for push notifications hub (#14758)

Automatic Merge

app/app_iface.go

@@ -902,7 +902,6 @@ type AppIface interface {
 	SlackUploadFile(slackPostFile *SlackFile, uploads map[string]*zip.File, teamId string, channelId string, userId string, slackTimestamp string) (*model.FileInfo, bool)
 	SoftDeleteTeam(teamId string) *model.AppError
 	Srv() *Server
-	StartPushNotificationsHubWorkers()
 	SubmitInteractiveDialog(request model.SubmitDialogRequest) (*model.SubmitDialogResponse, *model.AppError)
 	SwitchEmailToLdap(email, password, code, ldapLoginId, ldapPassword string) (string, *model.AppError)
 	SwitchEmailToOAuth(w http.ResponseWriter, r *http.Request, email, password, code, service string) (string, *model.AppError)