Add testing config for mixed image autoupgrade

This also removes the stale 'DirectCompositionGpuVSync' experiment from
testing config since a size presubmit was failing. This was the only
stale experiment found in the json file (found using cleanup.py from
crbug.com/1053702).

Bug: 1042877
Change-Id: I632e19f837c7566849cc3d4477732084765ffa12
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2399133
Commit-Queue: Carlos IL <carlosil@chromium.org>
Reviewed-by: Mark Pearson <mpearson@chromium.org>
Auto-Submit: Carlos IL <carlosil@chromium.org>
Cr-Commit-Position: refs/heads/master@{#805546}

testing/variations/fieldtrial_testing_config.json

@@ -51,6 +51,27 @@
             ]
         }
     ],
+    "AllPassiveMixedContentAutoupgrade": [
+        {
+            "platforms": [
+                "android",
+                "chromeos",
+                "linux",
+                "mac"
+            ],
+            "experiments": [
+                {
+                    "name": "Enabled_10",
+                    "params": {
+                        "mode": "all-passive"
+                    },
+                    "enable_features": [
+                        "AutoupgradeMixedContent"
+                    ]
+                }
+            ]
+        }
+    ],
     "AndroidDarkSearch": [
         {
             "platforms": [
@@ -1867,22 +1888,6 @@
             ]
         }
     ],
-    "DirectCompositionGpuVSync": [
-        {
-            "platforms": [
-                "windows"
-            ],
-            "experiments": [
-                {
-                    "name": "Enabled",
-                    "enable_features": [
-                        "DirectCompositionGpuVSync",
-                        "DirectCompositionPresentationFeedback"
-                    ]
-                }
-            ]
-        }
-    ],
     "DirectCompositionSoftwareOverlays": [
         {
             "platforms": [