Minor Telephony Unit test cleanup fixes

- Simplify Looper initialization code
- Don't catch and re-throw exceptions in
  testWithTelephonyFeatureAndCompatChanges (hiding call stack)
- Use @Mock annotation instead of manual assignment

Bug: 365800992
Test: com.android.phone.PhoneInterfaceManagerTest
Flag: TEST_ONLY
Change-Id: I248cc4267ca543899bbe5f8473481c646130008a
diff --git a/tests/src/com/android/TelephonyTestBase.java b/tests/src/com/android/TelephonyTestBase.java
index d72d85e..2bc7bb9 100644
--- a/tests/src/com/android/TelephonyTestBase.java
+++ b/tests/src/com/android/TelephonyTestBase.java
@@ -51,19 +51,11 @@
 
     @Before
     public void setUp() throws Exception {
-        mContext = spy(new TestContext());
-        // Set up the looper if it does not exist on the test thread.
         if (Looper.myLooper() == null) {
             Looper.prepare();
-            // Wait until the looper is not null anymore
-            for(int i = 0; i < 5; i++) {
-                if (Looper.myLooper() != null) {
-                    break;
-                }
-                Looper.prepare();
-                Thread.sleep(100);
-            }
         }
+
+        mContext = spy(new TestContext());
     }
 
     @After