🐛 Entry to instance encounters (mostly) doesn't handle failed entry requirement checks

[MowFord]

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OS / platform the server is running (if known)

Branch affected by issue

base

Steps to reproduce

My work here made me realize that all calls to xi.instance.onEventUpdate (which checks the requirements of entry) do nothing with the return, excepting Antiquated_Sluice_Gate

even that one doesn't actually handle a return of false properly, all of these will leave the initiator stuck in the entry event, waiting for an instance callback that will never come because someone in the party, within range, didn't meet the requirements

They should all have some kind of logic similar to _20m. Note that none of these actually work like the Nyzul entry npc as the event doesn't continuously check for a valid status, but checking if a return of false surely can be cleanly handled to exit the player out of the client-locking event

Expected behavior