Update PreconnectToSearch in field trial testing config

Add skip_in_background to field trial testing config

Bug: 1032153
Change-Id: Ie9fe3b94ad1b7fce3233a469a2c56ed383de0349
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2621888Reviewed-by: Ryan Sturm <ryansturm@chromium.org>
Commit-Queue: Tarun Bansal <tbansal@chromium.org>
Cr-Commit-Position: refs/heads/master@{#842115}

testing/variations/fieldtrial_testing_config.json

@@ -5819,6 +5819,7 @@
                 {
                     "name": "EnabledWithoutStartupDelay",
                     "params": {
+                        "skip_in_background": "true",
                         "startup_delay_ms": "0"
                     },
                     "enable_features": [
@@ -6415,22 +6416,6 @@
             ]
         }
     ],
-    "ResourceLoadingHints": [
-        {
-            "platforms": [
-                "android",
-                "android_weblayer"
-            ],
-            "experiments": [
-                {
-                    "name": "Enabled2",
-                    "enable_features": [
-                        "ResourceLoadingHints"
-                    ]
-                }
-            ]
-        }
-    ],
     "RevampedContextMenu": [
         {
             "platforms": [