Fix flaky test for persistent notifications

Persistent notifications test sometimes fails due
to setup activity doesn't exit due to failed intent.
Adding setup exit command when on device tests are starting and
adding timeout for transition.

Test: m Settings && adb install -r $ANDROID_PRODUCT_OUT/system_ext/priv-app/Settings/Settings.apk
Flag: EXEMPT bugfix
Bug: 349820489
Change-Id: Iaf1c1f481612367bbce919b27e89f88a24abb582

tests/Enable16KbTests/src/com/android/test/Enable16KbTest.java

@@ -76,11 +76,13 @@ public class Enable16KbTest extends BaseHostJUnit4Test {
         installTestApp();
 
         // Enable developer option and switch to 16kb kernel and Check page size
+        getDevice().enableAdbRoot();
         runTestAndWait(SWITCH_TO_16KB);
         result = getDevice().executeShellCommand("getconf PAGE_SIZE");
         assertEquals("16384", result.strip());
 
         // switch back to 4kb kernel and check page size
+        getDevice().enableAdbRoot();
         runTestAndWait(SWITCH_TO_4KB);
         result = getDevice().executeShellCommand("getconf PAGE_SIZE");
         assertEquals("4096", result.strip());