chore(ssh): remove stale mux cleanup job

Drop the scheduled stale multiplexed connection cleanup job, its SSH mux
health/orphan config, and the tests that covered that cleanup path.

app/Console/Kernel.php

@@ -8,7 +8,6 @@ use App\Jobs\CheckHelperImageJob;
 use App\Jobs\CheckTraefikVersionJob;
 use App\Jobs\CleanupInstanceStuffsJob;
 use App\Jobs\CleanupOrphanedPreviewContainersJob;
-use App\Jobs\CleanupStaleMultiplexedConnections;
 use App\Jobs\PullChangelog;
 use App\Jobs\PullTemplatesFromCDN;
 use App\Jobs\RegenerateSslCertJob;
@@ -41,9 +40,6 @@ class Kernel extends ConsoleKernel
             $this->instanceTimezone = config('app.timezone');
         }
 
-        $this->scheduleInstance->job(new CleanupStaleMultiplexedConnections, crons_queue())
-            ->hourly()
-            ->onOneServer();
         $this->scheduleInstance->command('cleanup:redis --clear-locks')->daily();
         $this->scheduleInstance->command('sanctum:prune-expired --hours=1')->hourly()->onOneServer();
         $this->scheduleInstance->job(new ApiTokenExpirationWarningJob)->hourly()->onOneServer();