Add HostResolverDispatch to fieldtrial_testing_config

This will allow us to start experimenting in Beta.

R=asvitkine@chromium.org

Change-Id: I7a93235c712b1f24015058c02417899c5cc5914d
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2517224
Auto-Submit: David Schinazi <dschinazi@chromium.org>
Commit-Queue: Alexei Svitkine <asvitkine@chromium.org>
Reviewed-by: Alexei Svitkine <asvitkine@chromium.org>
Cr-Commit-Position: refs/heads/master@{#824005}

testing/variations/fieldtrial_testing_config.json

@@ -3290,6 +3290,27 @@
             ]
         }
     ],
+    "HostResolverDispatch": [
+        {
+            "platforms": [
+                "android",
+                "android_webview",
+                "chromeos",
+                "ios",
+                "linux",
+                "mac",
+                "windows"
+            ],
+            "experiments": [
+                {
+                    "name": "0:0:0:0:0:0:64",
+                    "enable_features": [
+                        "DNSConcurrencyDoesNotUseFeatures"
+                    ]
+                }
+            ]
+        }
+    ],
     "IOSCrashReportBreadcrumbs": [
         {
             "platforms": [