APIs to disable data usage notifications.

Certain carriers have requested the ability to disable the warning,
limit, and rapid data usage notifications shown by the OS, so give
them that ability on a per-subId basis.  (The notifications are still
enabled by default.)

Unhide NOT_CONGESTED to match setSubscriptionOverrideCongested().

Fix bug in getPrimarySubscriptionPlanLocked() to find the first
currently active plan; the first non-recurring plan may be no longer
active.  Fix bug in SubscriptionPlan which allowed invalid negative
or zero-length Period objects.

Bug: 77851691, 77506882, 77662747
Test: atest com.android.server.NetworkPolicyManagerServiceTest
Test: atest android.telephony.cts.SubscriptionManagerTest
Exempt-From-Owner-Approval: SDK deadline, responding to API feedback
Change-Id: Ib6e6dbadd5022937c3f0661ab4b66aa617f0b5af
diff --git a/core/java/android/net/NetworkCapabilities.java b/core/java/android/net/NetworkCapabilities.java
index c314a35..a8e8179 100644
--- a/core/java/android/net/NetworkCapabilities.java
+++ b/core/java/android/net/NetworkCapabilities.java
@@ -254,9 +254,8 @@
     /**
      * Indicates that this network is not congested.
      * <p>
-     * When a network is congested, the device should defer network traffic that
-     * can be done at a later time without breaking developer contracts.
-     * @hide
+     * When a network is congested, applications should defer network traffic
+     * that can be done at a later time, such as uploading analytics.
      */
     public static final int NET_CAPABILITY_NOT_CONGESTED = 20;