Don't update mute when reaching the user count threshold.

[toger5]

Fixes: #2464

The idea is to mute whenever the participant count reaches 8 or more ppl. since there is a high chance for multiple users joining at the same time we update the mute state whenever we reach over 8ppl. So that a scheduled meeting still starts with everyone muted even though the meeting looked empty when the users were still in the lobby.

This changes it to only check this condition once at the beginningof the lobby and where the call just loaded (the client knows the user account)

[robintown]

This looks fine though I wonder if it would be more idiomatic as:

useEffect(() => {
  if (memberships.length >= MUTE_PARTICIPANT_COUNT)
    muteStates.audio.setEnabled?.(false)
}, [])

without the useCallback

[toger5]

This looks fine though I wonder if it would be more idiomatic as:

I added it to allow for the upgrade path to useEffectEvent. But for now the simpler version is reasonable.