Remove ProactivelyThrottleLowPriorityRequests entry from testing config.

Bug: 1126640
Change-Id: Idf2906985b34d3b69556e55fb745a9d23acf526a
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2629567Reviewed-by: Tarun Bansal <tbansal@chromium.org>
Commit-Queue: Caitlin Fischer <caitlinfischer@google.com>
Cr-Commit-Position: refs/heads/master@{#843586}

testing/variations/fieldtrial_testing_config.json

@@ -5496,32 +5496,6 @@
             ]
         }
     ],
-    "ProactivelyThrottleLowPriorityRequests": [
-        {
-            "platforms": [
-                "android",
-                "android_weblayer",
-                "chromeos",
-                "linux",
-                "mac",
-                "windows"
-            ],
-            "experiments": [
-                {
-                    "name": "Enabled_20190722",
-                    "params": {
-                        "http_rtt_multiplier_for_proactive_throttling_2G": "1.0",
-                        "http_rtt_multiplier_for_proactive_throttling_3G": "1.0",
-                        "http_rtt_multiplier_for_proactive_throttling_Slow-2G": "1.0",
-                        "queued_requests_dispatch_periodicity_ms": "5"
-                    },
-                    "enable_features": [
-                        "ProactivelyThrottleLowPriorityRequests"
-                    ]
-                }
-            ]
-        }
-    ],
     "ProbabilisticCryptidRenderer": [
         {
             "platforms": [