Disables crostini.LaunchBrowser.artifact as more often than not fails

On kevin.

BUG=1141944
TEST=test only change
TBR=sidereal@google.com

Change-Id: I3e05a2dfe7c5e6483b6de1155e405ef2c07527ce
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2495880Reviewed-by: Scott Violet <sky@chromium.org>
Commit-Queue: Scott Violet <sky@chromium.org>
Cr-Commit-Position: refs/heads/master@{#820422}

chromeos/BUILD.gn

@@ -326,6 +326,9 @@ if (is_chromeos_device) {
       # crbug.com/1131304
       "printer.PinPrintLexmark.no_pin",
       "printer.PinPrintLexmark.pin",
+
+      # crbug.com/1141944
+      "crostini.LaunchBrowser.artifact",
     ]
   }