Convert from Handlers to Executors in NotificationLockscreenUserManager

Removal of TestableLooper also means these tests can now run deviceless, so I've made that conversion as well.

Fixes: 315363596
Test: atest NotificationLockscreenUserManagerTest
Test: atest NotificationLockscreenUserManagerMainThreadTest
Test: atest SystemUiRoboTests
Flag: NA
Change-Id: Ie0adfcb9766593b2745791f040d8e3dbbd3e2240
diff --git a/packages/SystemUI/Android.bp b/packages/SystemUI/Android.bp
index d3a89f4..d61ae7e 100644
--- a/packages/SystemUI/Android.bp
+++ b/packages/SystemUI/Android.bp
@@ -438,6 +438,7 @@
         "androidx.core_core-animation-testing",
         "androidx.test.ext.junit",
         "inline-mockito-robolectric-prebuilt",
+        "platform-parametric-runner-lib",
     ],
     libs: [
         "android.test.runner",