Fix SimDialogActivityTest

Can't create handler inside thread

Bug: 323649089
Test: atest SimDialogActivityTest
Change-Id: I678a1a1841ab1e1cd87c358fbb3d52cbfb55dbe4
diff --git a/tests/unit/src/com/android/settings/sim/SimDialogActivityTest.kt b/tests/unit/src/com/android/settings/sim/SimDialogActivityTest.kt
index 9546d69..18a6f0b 100644
--- a/tests/unit/src/com/android/settings/sim/SimDialogActivityTest.kt
+++ b/tests/unit/src/com/android/settings/sim/SimDialogActivityTest.kt
@@ -45,10 +45,11 @@
     @Mock
     private lateinit var userManager: UserManager
 
-    private var activity = MockSimDialogActivity()
+    private lateinit var activity: SimDialogActivity
 
     @Before
     fun setUp() {
+        activity = MockSimDialogActivity()
         whenever(context.userManager).thenReturn(userManager)
         whenever(userManager.isGuestUser).thenReturn(false)
         whenever(userManager.hasUserRestriction(UserManager.DISALLOW_CONFIG_MOBILE_NETWORKS))