Re-add field trial testing config for DisableLatencyRecoveryDesktop

Based on the data gathered from running the experiment on canary/dev and
beta, it seems that the disabling latency recovery for both main and
impl threads is an overall performance win. So, we are going to
re-enable the (now-expired) experiment on stable and move forward with
its gradual rollout.

Bug: 993895
Change-Id: I5c45c3cb469d14cf53193d0af6a560842ce02be2
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2309188Reviewed-by: Robert Kaplow <rkaplow@chromium.org>
Commit-Queue: Mohsen Izadi <mohsen@chromium.org>
Cr-Commit-Position: refs/heads/master@{#790549}

testing/variations/fieldtrial_testing_config.json

@@ -2237,6 +2237,25 @@
             ]
         }
     ],
+    "DisableLatencyRecoveryDesktop": [
+        {
+            "platforms": [
+                "chromeos",
+                "linux",
+                "mac",
+                "windows"
+            ],
+            "experiments": [
+                {
+                    "name": "DisabledImplDisabledMain",
+                    "disable_features": [
+                        "ImplLatencyRecovery",
+                        "MainLatencyRecovery"
+                    ]
+                }
+            ]
+        }
+    ],
     "DisableMalwareExtensionsRemotely": [
         {
             "platforms": [