WireGuard outbound: Remove remoteDNS' "local" mode and domainStrategy (#6771)

https://github.com/XTLS/Xray-core/issues/6567#issuecomment-5660953757
https://github.com/XTLS/Xray-core/pull/6771#issuecomment-5751826982
https://github.com/XTLS/Xray-core/pull/6771#issuecomment-5751831637

proxy/wireguard/config.proto

@@ -17,13 +17,6 @@ message PeerConfig {
 }
 
 message DeviceConfig {
-  enum DomainStrategy {
-    FORCE_IP = 0;
-    FORCE_IP4 = 1;
-    FORCE_IP6 = 2;
-    FORCE_IP46 = 3;
-    FORCE_IP64 = 4;
-  }
   string secret_key = 1;
   repeated string endpoint = 2;
   repeated PeerConfig peers = 3;
@@ -31,7 +24,6 @@ message DeviceConfig {
   int32 mtu = 4;
 
   bytes reserved = 6;
-  DomainStrategy domain_strategy = 7;
   bool is_client = 8;
   bool no_kernel_tun = 9;
   repeated string DNS = 10;