fix(sub): drop legacy freedom.domainStrategy from JSON sub template (#6609)

The JSON-subscription template still set settings.domainStrategy on its freedom outbound, the placement #6515 moved off everywhere else, so xray-core migrated it to sockopt with a deprecation warning on every load. AsIs is the core default when the key is absent, so dropping it changes nothing else.

Fixes #6482.

internal/sub/default.json

@@ -49,7 +49,6 @@
       "tag": "direct",
       "protocol": "freedom",
       "settings": {
-        "domainStrategy": "AsIs",
         "redirect": "",
         "noises": []
       }
@@ -89,4 +88,4 @@
     ]
   },
   "stats": {}
-}
+}