Remove Print As Image for Mac and Win

testing/variations/fieldtrial_testing_config.json

 {
     "AndroidSessionNotifications": [
         {
             "platforms": [
                 "android"
             ],
             "experiments": [
                 {
                     "name": "Disabled"
                 }
@@ skipping 1581 matching lines @@
                         "PreconnectMore"
                     ]
                 }
             ]
         }
     ],
     "PrintPdfAsImage": [
         {
             "platforms": [
                 "chromeos",
-                "linux",
-                "mac",
-                "win"
+                "linux"
             ],
             "experiments": [
                 {
                     "name": "Enabled",
                     "enable_features": [
                         "PrintPdfAsImage"
                     ]
                 }
             ]
         }
@@ skipping 912 matching lines @@
                 {
                     "name": "Enabled",
                     "enable_features": [
                         "use-new-media-cache"
                     ]
                 }
             ]
         }
     ]
 }