Address API review feedback

Address API review feedback to:
 - Rename NetworkAgent#setTeardownDelayMs to
   NetworkAgent#setTeardownDelayMillis
 - Use getters instead of fields in VpnTransportInfo
 - Rename registerDefaultNetworkCallbackAsUid to
   registerDefaultNetworkCallbackForUid in ConnectiivityManager

Bug: 183972850
Bug: 185246410
Fix: 184735863
Test: make update-api
Test: atest FrameworksNetTests
Test: atest CtsNetTestCasesLatestSdk
Change-Id: I5e8c4bed8bda40d507afa894c359b5e24ee5d868
Merged-In: I5e8c4bed8bda40d507afa894c359b5e24ee5d868
diff --git a/framework/api/system-current.txt b/framework/api/system-current.txt
index de673ee..fc65fec 100644
--- a/framework/api/system-current.txt
+++ b/framework/api/system-current.txt
@@ -238,7 +238,7 @@
     method public final void sendQosSessionLost(int, int, int);
     method public final void sendSocketKeepaliveEvent(int, int);
     method @Deprecated public void setLegacySubtype(int, @NonNull String);
-    method public void setTeardownDelayMs(@IntRange(from=0, to=0x1388) int);
+    method public void setTeardownDelayMillis(@IntRange(from=0, to=0x1388) int);
     method public final void setUnderlyingNetworks(@Nullable java.util.List<android.net.Network>);
     method public void unregister();
     field public static final int VALIDATION_STATUS_NOT_VALID = 2; // 0x2