fix(core): deprecation notices thrown at login/logout even if there's no...

... valid reason

Stops the wrongly thrown deprecated notices at login/logout for supposed deprecated usage of ['login', 'user'] and ['logout', 'user'] events even if there are no handlers registered for these deprecated events as mentioned in #6493.
I see. With this change, the dev would get the deprecation message only if a handler was registered for (login, user) directly. E.g. registering for (all, user) would not count. This makes sense to me.