arcvm: Don't stop mojo proxy when ARCVM stops

The proxy does that by itself today.

BUG=b:142140355
TEST=pkill crosvm, confirm ARCVM restarts and mojo works.

Change-Id: I72fae8dba5d5c134510e093288db1d1c90f12148
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2341996Reviewed-by: Ryo Hashimoto <hashimoto@chromium.org>
Commit-Queue: Yusuke Sato <yusukes@chromium.org>
Cr-Commit-Position: refs/heads/master@{#795767}

components/arc/session/arc_vm_client_adapter.cc

@@ -754,12 +754,7 @@ class ArcVmClientAdapter : public ArcClientAdapter,
   }
 
   void OnArcInstanceStopped() {
-    VLOG(1) << "ARCVM stopped. Stopping arcvm-server-proxy";
-
-    // TODO(yusukes): Consider removing this stop call once b/142140355 is
-    // implemented.
-    chromeos::UpstartClient::Get()->StopJob(
-        kArcVmServerProxyJobName, /*environment=*/{}, base::DoNothing());
+    VLOG(1) << "ARCVM stopped.";
 
     // If this method is called before even mini VM is started (e.g. very early
     // vm_concierge crash), or this method is called twice (e.g. crosvm crash