Refactor code incompatible with Mockito 2.7.13

(cherry picked from 76e319f015c2b43498ce3ce610a253d63e76cbf3)

Some additional internal only refactorings were done as well.

Bug: 32912773
Test: make checkbuild
Change-Id: I96e3da967fad731fc8f39bde9db95f50ab7353fb
diff --git a/services/tests/servicestests/src/com/android/server/devicepolicy/DevicePolicyManagerTest.java b/services/tests/servicestests/src/com/android/server/devicepolicy/DevicePolicyManagerTest.java
index f969e80..8987ac1 100644
--- a/services/tests/servicestests/src/com/android/server/devicepolicy/DevicePolicyManagerTest.java
+++ b/services/tests/servicestests/src/com/android/server/devicepolicy/DevicePolicyManagerTest.java
@@ -85,7 +85,6 @@
 import static org.mockito.Matchers.anyLong;
 import static org.mockito.Matchers.anyObject;
 import static org.mockito.Matchers.anyString;
-import static org.mockito.Matchers.argThat;
 import static org.mockito.Matchers.eq;
 import static org.mockito.Matchers.isNull;
 import static org.mockito.Mockito.atLeast;
@@ -99,6 +98,7 @@
 import static org.mockito.Mockito.verify;
 import static org.mockito.Mockito.verifyZeroInteractions;
 import static org.mockito.Mockito.when;
+import static org.mockito.hamcrest.MockitoHamcrest.argThat;
 
 /**
  * Tests for DevicePolicyManager( and DevicePolicyManagerService).