A return file pointing at gamescope-session-opengamepadui is a stale
self-reference: os-session-select writes the current autologin session to the
return file on every switch, and once an exclusive OGPU session is active that
session is OpenGamepadUI itself. Returning to it bounces straight back instead
of landing in Steam, so drop it from the valid return sessions.
Fixes broken input after returning from an exclusive OpenGamepadUI session:
the OGPU session leaves InputPlumber intercepting the gamepad in Block mode,
so Steam cannot read it. Restart InputPlumber before switching, and return to
the session recorded by os-session-select instead of hardcoding 'steam' so
the autologin config is preserved.
