extension_host: Fix SSH reconnect breaks language server (#32457)
Smit Barmase
created
Closes #29032
This PR fixes an issue where reconnecting to SSH Remote would result in
a broken language server.
This was caused by SSH clients not registering because the `ssh_clients`
map would still contain an entry from a previously killed SSH server.
For fix, now we also check if its value has been dropped.
Release Notes:
- Fixed issue where reconnecting to SSH Remote would result in broken
code completions and diagnostics.