Update fieldtrial testing config for plus addresses.

This CL does two things:
- It merges the configuration for syncing plus addresses into the main
  experiment to reflect a change of the Finch config that has already
  taken place.
- It enables PlusAddressAffiliations in the same experiment in
  anticipation of adding it to the Finch config.

Bug: 328083944
Change-Id: I015c872a6a59a415c84488343226e4386f06a1cb
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5715771
Reviewed-by: Norge Vizcay <vizcay@google.com>
Auto-Submit: Jan Keitel <jkeitel@google.com>
Commit-Queue: Jan Keitel <jkeitel@google.com>
Cr-Commit-Position: refs/heads/main@{#1328704}
diff --git a/testing/variations/fieldtrial_testing_config.json b/testing/variations/fieldtrial_testing_config.json
index 7470749a..9eced0e 100644
--- a/testing/variations/fieldtrial_testing_config.json
+++ b/testing/variations/fieldtrial_testing_config.json
@@ -16519,11 +16519,13 @@
                 {
                     "name": "Enabled",
                     "enable_features": [
+                        "PlusAddressAffiliations",
                         "PlusAddressRefresh",
                         "PlusAddressRefreshUiInAndroid",
                         "PlusAddressRefreshUiInDesktopModal",
                         "PlusAddressRefreshUiInIOS",
-                        "PlusAddressesEnabled"
+                        "PlusAddressesEnabled",
+                        "SyncPlusAddress"
                     ]
                 }
             ]
@@ -21778,27 +21780,6 @@
             ]
         }
     ],
-    "SyncPlusAddress": [
-        {
-            "platforms": [
-                "android",
-                "chromeos",
-                "chromeos_lacros",
-                "ios",
-                "linux",
-                "mac",
-                "windows"
-            ],
-            "experiments": [
-                {
-                    "name": "Enabled",
-                    "enable_features": [
-                        "SyncPlusAddress"
-                    ]
-                }
-            ]
-        }
-    ],
     "SyncSegmentsData": [
         {
             "platforms": [