Remove HostResolverDispatch from fieldtrial_testing_config

This should have been done as part of crrev.com/c/2636880
yesterday, and will allow us to launch the change.

R=renjietang@chromium.org

Bug: 1134205
Change-Id: Ie05c602d83bb9bbf84c9cb7ec3baaea816377b1a
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2641168
Commit-Queue: David Schinazi <dschinazi@chromium.org>
Commit-Queue: Renjie Tang <renjietang@chromium.org>
Auto-Submit: David Schinazi <dschinazi@chromium.org>
Reviewed-by: Renjie Tang <renjietang@chromium.org>
Cr-Commit-Position: refs/heads/master@{#845461}

testing/variations/fieldtrial_testing_config.json

@@ -3211,27 +3211,6 @@
             ]
         }
     ],
-    "HostResolverDispatch": [
-        {
-            "platforms": [
-                "android",
-                "android_webview",
-                "chromeos",
-                "ios",
-                "linux",
-                "mac",
-                "windows"
-            ],
-            "experiments": [
-                {
-                    "name": "0:0:0:0:0:0:64",
-                    "enable_features": [
-                        "DNSConcurrencyDoesNotUseFeatures"
-                    ]
-                }
-            ]
-        }
-    ],
     "IOSCrashReportBreadcrumbs": [
         {
             "platforms": [