Add finch testing config for VizHitTestSurfaceLayer

Bug: 874919
Change-Id: Ie4f550e1dcc98e5f8375ab13ade31de4143dc0ab
Reviewed-on: https://chromium-review.googlesource.com/c/1474331Reviewed-by: Jesse Doherty <jwd@chromium.org>
Reviewed-by: Ria Jiang <riajiang@chromium.org>
Reviewed-by: Robert Flack <flackr@chromium.org>
Commit-Queue: Xianda Sun <sunxd@chromium.org>
Cr-Commit-Position: refs/heads/master@{#634427}

testing/variations/fieldtrial_testing_config.json

@@ -5395,7 +5395,7 @@
             ]
         }
     ],
-    "VizHitTestDrawQuad": [
+    "VizHitTest": [
         {
             "platforms": [
                 "android",
@@ -5406,8 +5406,11 @@
             ],
             "experiments": [
                 {
-                    "name": "Enabled",
+                    "name": "VizHitTestSurfaceLayer",
                     "enable_features": [
+                        "VizHitTestSurfaceLayer"
+                    ],
+                    "disable_features": [
                         "VizHitTestDrawQuad"
                     ]
                 }