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

This reverts commit 854d09d1.

Reason for revert: New LKGM 12105.0.0 has landed

Original change's description:
> 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}

TBR=stevenjb@chromium.org,achuith@chromium.org,bpastene@chromium.org,agawronska@chromium.org

Change-Id: I8171e93bf1a4f75444749ae1bb564f4986f955a2

Bug: 954192
Change-Id: I8171e93bf1a4f75444749ae1bb564f4986f955a2
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1575112Reviewed-by: Aga Wronska <agawronska@chromium.org>
Reviewed-by: Ben Pastene <bpastene@chromium.org>
Reviewed-by: Achuith Bhandarkar <achuith@chromium.org>
Commit-Queue: Achuith Bhandarkar <achuith@chromium.org>
Cr-Commit-Position: refs/heads/master@{#652648}

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 = [ "security.SELinuxFilesNonARC" ]  # crbug.com/954192
+    tast_disabled_tests = []
   }
   tast_test("chrome_kevin_tast_tests") {
     # Tests that fail on Kevin devices.