Remove Windows occlusion studies from the testing config.

-NativeWindowOcclusionTrackerWin
-WebContentsOcclusionWin

Bug: 1126640, 668690, 813093
Change-Id: I5312a98fdf17e7b2b34e832073c1c4231af45e71
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2500543
Commit-Queue: Caitlin Fischer <caitlinfischer@google.com>
Reviewed-by: David Bienvenu <davidbienvenu@chromium.org>
Cr-Commit-Position: refs/heads/master@{#823025}

testing/variations/fieldtrial_testing_config.json

@@ -4443,21 +4443,6 @@
             ]
         }
     ],
-    "NativeWindowOcclusionTrackerWin": [
-        {
-            "platforms": [
-                "windows"
-            ],
-            "experiments": [
-                {
-                    "name": "NativeWindowOcclusionTrackerWin",
-                    "enable_features": [
-                        "CalculateNativeWinOcclusion"
-                    ]
-                }
-            ]
-        }
-    ],
     "NavigationPredictor": [
         {
             "platforms": [
@@ -7688,21 +7673,6 @@
             ]
         }
     ],
-    "WebContentsOcclusionWin": [
-        {
-            "platforms": [
-                "windows"
-            ],
-            "experiments": [
-                {
-                    "name": "WebContentsOcclusionWin",
-                    "enable_features": [
-                        "WebContentsOcclusion"
-                    ]
-                }
-            ]
-        }
-    ],
     "WebProtectConnectors": [
         {
             "platforms": [