No-op refactoring of VPN lockdown status check.

Currently, if VPN lockdown is disabled, the blocking judgement
inside VPN will return false immediately. It will make
ConnectivityService hard to check blocked status by a given
VPN lockdown status.

Thus, move this check into ConnectivityService and check it
externally.

Bug: 117814902
Test: 1. manual test with 3rd-party vpn app
      2. runtest frameworks-net

Change-Id: Ia8319b1a1a12f1058c24badf2431f2ec69bc78e7
diff --git a/services/core/java/com/android/server/ConnectivityService.java b/services/core/java/com/android/server/ConnectivityService.java
index 1c8d99a..e300d8a 100644
--- a/services/core/java/com/android/server/ConnectivityService.java
+++ b/services/core/java/com/android/server/ConnectivityService.java
@@ -1143,7 +1143,7 @@
         }
         synchronized (mVpns) {
             final Vpn vpn = mVpns.get(UserHandle.getUserId(uid));
-            if (vpn != null && vpn.isBlockingUid(uid)) {
+            if (vpn != null && vpn.getLockdown() && vpn.isBlockingUid(uid)) {
                 return true;
             }
         }
@@ -1736,7 +1736,7 @@
             // list all state depending on the return value of this function has to be recomputed.
             // TODO: add a trigger when the always-on VPN sets its blocked UIDs to reevaluate and
             // send the necessary onBlockedStatusChanged callbacks.
-            if (vpn != null && vpn.isBlockingUid(uid)) {
+            if (vpn != null && vpn.getLockdown() && vpn.isBlockingUid(uid)) {
                 return true;
             }
         }