Disable ui.ChromeLoginGAIA while we work on supporting RequiredVar tests

This test requires 2 Tast vars. Simple Chrome currently doesn't fetch
the internal tast vars repo. So disable this test while we figure it
out.

Bug: 1115622
Change-Id: I31c7404e4eecdff965143a2f3430b114f85e9eca
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2353064
Commit-Queue: Ben Pastene <bpastene@chromium.org>
Commit-Queue: Achuith Bhandarkar <achuith@chromium.org>
Auto-Submit: Ben Pastene <bpastene@chromium.org>
Reviewed-by: Achuith Bhandarkar <achuith@chromium.org>
Cr-Commit-Position: refs/heads/master@{#797434}

chromeos/BUILD.gn

@@ -287,6 +287,9 @@ if (is_chromeos_device) {
   tast_test("chrome_all_tast_tests") {
     # To disable a specific test, add it the following list and cite a bug.
     tast_disabled_tests = [
+      # crbug.com/1115622
+      "ui.ChromeLoginGAIA",
+
       # crbug.com/1097630
       "security.OpenFDs",