Field trial testing config for AutofillAssistantDirectActions.

This patch introduces a test config for the
AutofillAssistantDirectActions approved for the M81 Beta channel. The
corresponding finch config cl is in review and prompted this change.

Bug: b/148647596
Change-Id: Ia85e56c96afaea805c8e65b10a50b1549c93cbaa
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2077740Reviewed-by: Mark Pearson <mpearson@chromium.org>
Commit-Queue: Mathias Carlen <mcarlen@chromium.org>
Cr-Commit-Position: refs/heads/master@{#745415}

testing/variations/fieldtrial_testing_config.json

@@ -641,6 +641,22 @@
             ]
         }
     ],
+    "AutofillAssistantDirectActionsLaunch": [
+        {
+            "platforms": [
+                "android"
+            ],
+            "experiments": [
+                {
+                    "//1": "This launch is gated external to Chrome.",
+                    "name": "Enabled",
+                    "enable_features": [
+                        "AutofillAssistantDirectActions"
+                    ]
+                }
+            ]
+        }
+    ],
     "AutofillCompany": [
         {
             "platforms": [