Revert "Revert "Enable ADVANCED_VPN_ENABLED For Droidfood""

This reverts commit ecd21b737a.

Reason for revert:

1. The original revert does not solve flaky test failure, still saw similar new bugs. For example: b/275474028, b/270612944 and b/268326421.
2. The flag has nothing to do with the failed tests.

Change-Id: I8dd069d0c4af3469ad29a221c9c706856e577d48

packages/SystemUI/src/com/android/systemui/flags/Flags.kt

@@ -701,6 +701,6 @@ object Flags {
 
     // TODO(b/272805037): Tracking Bug
     @JvmField
-    val ADVANCED_VPN_ENABLED = unreleasedFlag(2800, name = "AdvancedVpn__enable_feature",
-            namespace = "vpn", teamfood = true)
+    val ADVANCED_VPN_ENABLED = releasedFlag(2800, name = "AdvancedVpn__enable_feature",
+            namespace = "vpn")
 }