Add PhysicalWeb to the fieldtrial testing config

testing/variations/fieldtrial_testing_config_android.json

 {
     "AndroidSessionNotifications": [
         {
             "group_name": "Disabled"
         }
     ],
     "AsyncDns": [
         {
             "group_name": "AsyncDnsA"
         },
@@ skipping 190 matching lines @@
     "PageRevisitInstrumentation": [
         {
             "group_name": "Enabled"
         }
     ],
     "PasswordBranding": [
         {
             "group_name": "SmartLockBrandingSavePromptOnly"
         }
     ],
+    "PhysicalWeb": [
+        {
+            "group_name": "Enabled"
+        }
+    ],
     "Precache": [
         {
             "group_name": "Enabled"
         }
     ],
     "ProgressBarAnimationAndroid": [
         {
             "group_name": "SmoothAnimation",
             "params": {
                 "progress-bar-animation": "smooth"
@@ skipping 195 matching lines @@
         {
             "group_name": "Enabled"
         }
     ],
     "WebRTC-PeerConnectionDTLS1.2": [
         {
             "group_name": "Enabled"
         }
     ]
 }