Add @UnsupportedAppUsage to test apis that are known to be used by apps.

go/testapi-enforcement

Bug: 133832325
Test: m
Change-Id: Ifc8db120640a1554dcbf1722e61e09c7ddc65dd6
Merged-In: Ifc8db120640a1554dcbf1722e61e09c7ddc65dd6
diff --git a/core/java/android/app/usage/NetworkStatsManager.java b/core/java/android/app/usage/NetworkStatsManager.java
index 8e40449..6bade90 100644
--- a/core/java/android/app/usage/NetworkStatsManager.java
+++ b/core/java/android/app/usage/NetworkStatsManager.java
@@ -146,6 +146,7 @@
     }
 
     /** @hide */
+    @UnsupportedAppUsage
     @TestApi
     public void setPollForce(boolean pollForce) {
         if (pollForce) {