Disable XR browser tests on RX 550

Disables the XR browser tests on the RX 550 tester, as the tests
randomly hang indefinitely on this hardware configuration.

TBR=ynovikov@chromium.org

Bug: 1018896
Change-Id: Ie874c7df846d5133cd91fcf03eb7592e4c2b1347
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1884278Reviewed-by: Brian Sheedy <bsheedy@chromium.org>
Reviewed-by: Yuly Novikov <ynovikov@chromium.org>
Commit-Queue: Brian Sheedy <bsheedy@chromium.org>
Cr-Commit-Position: refs/heads/master@{#710145}

testing/buildbot/chromium.gpu.fyi.json

@@ -20296,29 +20296,6 @@
           "expiration": 21600
         },
         "test": "swiftshader_unittests"
-      },
-      {
-        "args": [
-          "--ignore-runtime-requirements=*"
-        ],
-        "merge": {
-          "args": [],
-          "script": "//testing/merge_scripts/standard_gtest_merge.py"
-        },
-        "name": "xr_browser_tests",
-        "swarming": {
-          "can_use_on_swarming_builders": true,
-          "containment_type": "AUTO",
-          "dimension_sets": [
-            {
-              "gpu": "1002:699f",
-              "os": "Windows-10",
-              "pool": "Chrome-GPU"
-            }
-          ],
-          "expiration": 21600
-        },
-        "test": "xr_browser_tests"
       }
     ],
     "isolated_scripts": [

testing/buildbot/test_suite_exceptions.pyl

@@ -2133,6 +2133,8 @@
       'Win7 FYI Debug (AMD)',
       # Fails on the bot, http://crbug.com/868143
       'Win7 FYI Release (AMD)',
+      # Randomly hangs indefinitely https://crbug.com/1018896.
+      'Win10 FYI x64 Release (AMD RX 550)',
     ],
   },
 }