Disallow specifying custom resolver name for STRICT and LOGICAL dns (#6799)

Signed-off-by: Sumukh Shivaprakash <sumukhs@microsoft.com>

Mirrored from https://github.com/envoyproxy/envoy @ e3ca81f163a74bdeb0b98f888a8789ba7d11acd9

envoy/api/v2/core/address.proto

@@ -53,10 +53,11 @@ message SocketAddress {
     // named resolver is capable of named port resolution.
     string named_port = 4;
   }
-  // The name of the resolver. This must have been registered with Envoy. If this is
-  // empty, a context dependent default applies. If address is a hostname this
-  // should be set for resolution other than DNS. If the address is a concrete
-  // IP address, no resolution will occur.
+  // The name of the custom resolver. This must have been registered with Envoy. If
+  // this is empty, a context dependent default applies. If the address is a concrete
+  // IP address, no resolution will occur. If address is a hostname this
+  // should be set for resolution other than DNS. Specifying a custom resolver with
+  // *STRICT_DNS* or *LOGICAL_DNS* will generate an error at runtime.
   string resolver_name = 5;
 
   // When binding to an IPv6 address above, this enables `IPv4 compatibility