[VPN] Update server-status VPN API endpoint (#36627)

On Mac, we use a server-status endpoint for OnDemand VPN functionality.
The change upgrades the old (current) API `/vpnsrv/api/server-status`,
to the new one: `/api/v1.3/server-status`. The API responses are
claimed by Guardian to be identical, zero behavioural change.

components/brave_vpn/browser/connection/ikev2/mac/ikev2_connection_api_impl_mac.mm

@@ -19,6 +19,7 @@
 #include "base/logging.h"
 #include "base/strings/sys_string_conversions.h"
 #include "brave/components/brave_vpn/browser/connection/brave_vpn_connection_manager.h"
+#include "brave/components/brave_vpn/common/brave_vpn_constants.h"
 #include "brave/components/brave_vpn/common/pref_names.h"
 #include "components/prefs/pref_service.h"
 #include "services/network/public/cpp/shared_url_loader_factory.h"
@@ -215,10 +216,11 @@ void IKEv2ConnectionAPIImplMac::CreateVPNConnectionImpl(
       vpn_server_connect_rule.interfaceTypeMatch =
           NEOnDemandRuleInterfaceTypeAny;
       vpn_server_connect_rule.probeURL = [NSURL
-          URLWithString:
-              [NSString
-                  stringWithFormat:@"https://%@/vpnsrv/api/server-status",
-                                   base::SysUTF8ToNSString(info.hostname())]];
+          URLWithString:[NSString stringWithFormat:@"https://%@/%@",
+                                                   base::SysUTF8ToNSString(
+                                                       info.hostname()),
+                                                   base::SysUTF8ToNSString(
+                                                       kServerStatus)]];
       [vpn_manager setOnDemandRules:@[ vpn_server_connect_rule ]];
     }
 

components/brave_vpn/common/brave_vpn_constants.h

@@ -53,6 +53,7 @@ inline constexpr char kCredential[] = "api/v1.3/device/";
 inline constexpr char kVerifyPurchaseToken[] = "api/v1.1/verify-purchase-token";
 inline constexpr char kCreateSubscriberCredentialV12[] =
     "api/v1.2/subscriber-credential/create";
+inline constexpr char kServerStatus[] = "api/v1.3/server-status";
 inline constexpr int kP3AIntervalHours = 24;
 
 inline constexpr char kSubscriberCredentialKey[] = "credential";