Enable signal strength based ECT capping

Around 30-40% more previews with no significant change in opt-out rate.
See the bug for details.

Change-Id: I299dc5f15e32033f2f463d3b49fc3f30e157593d
Bug: 924160
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1552573Reviewed-by: Ryan Sturm <ryansturm@chromium.org>
Reviewed-by: Robert Kaplow <rkaplow@chromium.org>
Commit-Queue: Tarun Bansal <tbansal@chromium.org>
Cr-Commit-Position: refs/heads/master@{#648303}

net/nqe/network_quality_estimator_params.cc

@@ -501,7 +501,7 @@ NetworkQualityEstimatorParams::NetworkQualityEstimatorParams(
           GetStringValueForVariationParamWithDefaultValue(
               params_,
               "cap_ect_based_on_signal_strength",
-              "false") == "true"),
+              "true") != "false"),
       upper_bound_typical_kbps_multiplier_(
           GetDoubleValueForVariationParamWithDefaultValue(
               params_,

testing/variations/fieldtrial_testing_config.json

@@ -3010,28 +3010,6 @@
             ]
         }
     ],
-    "NetworkQualityEstimator": [
-        {
-            "platforms": [
-                "android",
-                "windows",
-                "mac",
-                "chromeos",
-                "linux"
-            ],
-            "experiments": [
-                {
-                    "name": "Enabled9",
-                    "params": {
-                        "cap_ect_based_on_signal_strength": "true"
-                    },
-                    "enable_features": [
-                        "NetworkQualityEstimator"
-                    ]
-                }
-            ]
-        }
-    ],
     "NewExtensionUpdaterService": [
         {
             "platforms": [