Disconnect old websockets

[masenf]

Disconnect websockets more aggressively

• page beforeunload and unload
• when a new event comes in for the same token with a different sid (removed in this PR)

[codspeed-hq]

CodSpeed Performance Report

Merging #4953 will not alter performance

_{Comparing masenf/disconnect-old-websockets (486de31) with main (8f313ad)}

Summary

✅ 12 untouched benchmarks

[Lendemor]

Related to #4607 I think.

Disconnecting on new sid for same token means the original page will get disconnected?

[masenf]

Disconnecting on new sid for same token means the original page will get disconnected?

yes; this is intended to handle the case where page is refreshed (in an iframe) or hot reloaded and ends up with a new websocket, but never closes out the old one.

that said, i think the frontend logic might be good enough, and i wasn't actually able to hit that log message during actual testing.