io/socket: discard sockets which have failed to connect

Fixes future connection attempts.

changelog/next.md

@@ -12,3 +12,4 @@
 - Fixed `NotificationAction.text` not accepting text updates.
 - Fixed PipeWire route volume writes for devices without a reported volume step.
 - Fixed a crash when quitting or reloading while a `Loader` was still loading asynchronously.
+- Fixed future `Socket` connection attempts after a failed connection attempt.