Add tests for the network blocked status change

onBlockedStatusChanged is intruduced for network blocked status.
The changes in this patch are:
  - Test onBlockedStatusChanged which tells apps whether the
    network is blocked.
  - Fixed the tests which is affected by the order changed in
    onAvailable.

Test: as follows
    - runtest frameworks-net
    - runtest -x NetworkPolicyManagerServiceTest.java
Bug: 74575553
Change-Id: I383c037ed895ef69c478dc3cff69fb1e27c42845
diff --git a/services/core/java/com/android/server/ConnectivityService.java b/services/core/java/com/android/server/ConnectivityService.java
index b750d79..3850187 100644
--- a/services/core/java/com/android/server/ConnectivityService.java
+++ b/services/core/java/com/android/server/ConnectivityService.java
@@ -910,7 +910,8 @@
         registerPrivateDnsSettingsCallbacks();
     }
 
-    private Tethering makeTethering() {
+    @VisibleForTesting
+    protected Tethering makeTethering() {
         // TODO: Move other elements into @Overridden getters.
         final TetheringDependencies deps = new TetheringDependencies() {
             @Override