chromeos: Disable Tast test security.SELinuxFilesNonARC to unblock LKGM roll.

Unblocks https://chromium-review.googlesource.com/c/chromium/src/+/1573380

Bug: 954192
Change-Id: If338e6fd4cb28ba8a18996c786b87cea978366fa
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1574598
Commit-Queue: Ben Pastene <bpastene@chromium.org>
Reviewed-by: Achuith Bhandarkar <achuith@chromium.org>
Cr-Commit-Position: refs/heads/master@{#652420}

chromeos/BUILD.gn

@@ -231,7 +231,7 @@ if (is_cros_chrome_sdk) {
   # To diagnose tast failures or disable tests, see go/tast-failures
   tast_test("chrome_all_tast_tests") {
     # To disable a specific test, add it the following list.
-    tast_disabled_tests = []
+    tast_disabled_tests = [ "security.SELinuxFilesNonARC" ]  # crbug.com/954192
   }
   tast_test("chrome_kevin_tast_tests") {
     # Tests that fail on Kevin devices.