Adding Site Isolation Win bot filtering for WindowOpenPanelTest.WindowOpenFocus.

testing/buildbot/chromium.fyi.json

 {
   "Android Asan Builder Tests (dbg)": {
     "gtest_tests": [
       {
         "args": [
           "--tool=asan"
         ],
         "test": "android_webview_unittests"
       },
       {
@@ skipping 10928 matching lines @@
         "test": "extensions_unittests"
       },
       {
         "args": [
           "--isolate-extensions"
         ],
         "test": "installer_util_unittests"
       },
       {
         "args": [
-          "--isolate-extensions"
+          "--isolate-extensions",
+          "--test-launcher-filter-file=src/testing/buildbot/filters/isolate-extensions.interactive_ui_tests.filter"
         ],
         "test": "interactive_ui_tests"
       },
       {
         "args": [
           "--isolate-extensions"
         ],
         "test": "nacl_loader_unittests"
       },
       {
@@ skipping 577 matching lines @@
       },
       {
         "swarming": {
           "can_use_on_swarming_builders": true
         },
         "test": "views_unittests"
       }
     ]
   }
 }