sheriff: disable two PinPrintLexmark tast tests

They fail consistently on chromeos-kevin-rel.

Bug: 1131304
Change-Id: Id26ed4a30fb7b27d2326d92ac6f7baa9f61395e9
Tbr: batrapranav@chromium.org
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2426346
Commit-Queue: Elly Fong-Jones <ellyjones@chromium.org>
Reviewed-by: Elly Fong-Jones <ellyjones@chromium.org>
Cr-Commit-Position: refs/heads/master@{#809843}

chromeos/BUILD.gn

@@ -322,6 +322,10 @@ if (is_chromeos_device) {
       # crbug.com/1131496
       "apps.LaunchHelpApp.clamshell_oobe_stable",
       "apps.LaunchHelpApp.tablet_oobe_stable",
+
+      # crbug.com/1131304
+      "printer.PinPrintLexmark.no_pin",
+      "printer.PinPrintLexmark.pin",
     ]
   }