Disabled crostini.Restart.artifact because of flakiness

TBR=davidmunro@google.com

No-Presubmit: true

Bug: 1114654
Change-Id: I5fd08f1532e091654e3ebb601df7e04f06569c77
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2346244Reviewed-by: Andy Paicu <andypaicu@chromium.org>
Commit-Queue: Andy Paicu <andypaicu@chromium.org>
Cr-Commit-Position: refs/heads/master@{#796336}

chromeos/BUILD.gn

@@ -312,6 +312,9 @@ if (is_chromeos_device) {
 
       # crbug.com/1099695
       "platform.Drivefs",
+
+      # crbug.com/1114654
+      "crostini.Restart.artifact",
     ]
   }