Add fieldtrial_testing_config for EnableADPFSetThreads

Bug: 375364382
Change-Id: Iec7d45f5addfaa192fd4b9d26c27685e5c07f339
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5970995
Reviewed-by: Kartar Singh <kartarsingh@google.com>
Commit-Queue: Igor Kraskevich <kraskevich@google.com>
Cr-Commit-Position: refs/heads/main@{#1374560}

testing/variations/fieldtrial_testing_config.json

@@ -9040,6 +9040,21 @@
             ]
         }
     ],
+    "EnableADPFSetThreads": [
+        {
+            "platforms": [
+                "android"
+            ],
+            "experiments": [
+                {
+                    "name": "Enabled",
+                    "enable_features": [
+                        "EnableADPFSetThreads"
+                    ]
+                }
+            ]
+        }
+    ],
     "EnableBackForwardCacheForOngoingSubframeNavigation": [
         {
             "platforms": [