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