Changed ResourcePriority experiment names to match upcoming 50/50 trial.

testing/variations/fieldtrial_testing_config_mac.json

 {
     "AutofillClassifier": [
         {
             "group_name": "Enabled"
         }
     ],
     "AutofillFieldMetadata": [
         {
             "group_name": "Enabled"
         }
@@ skipping 148 matching lines @@
             "params": {
                 "sendingThreshold": "abcdef"
             }
         },
         {
             "group_name": "DontShowAndDontSend"
         }
     ],
     "ResourcePriorities": [
         {
-            "group_name": "AllExceptAsyncScripts_11011_1_1_10"
+            "group_name": "Launch50pct_11011_1_1_10"
         },
         {
-            "group_name": "Control"
+            "group_name": "Control50pct"
         }
     ],
     "SSLCommonNameMismatchHandling": [
         {
             "group_name": "Enabled"
         }
     ],
     "SafeBrowsingIncidentReportingService": [
         {
             "enable_features": [
@@ skipping 146 matching lines @@
     ],
     "use-new-media-cache": [
         {
             "enable_features": [
                 "use-new-media-cache"
             ],
             "group_name": "Enabled"
         }
     ]
 }