Do not consider embedded task as task switch

For example:
 Task A - TaskFragment - Activity X
        - TaskFragment - Task B (embedded) - Activity Y
If Y starts Activity Z in Task B, even if A and B are different,
we don't want to show starting window because B is a part of A
from user's perspective.

Bug: 197595621
Test: Start activity from embedded task fragment to the same
      task fragment.
Change-Id: I9ec40e77b675c857f46747babd3144b2989042f6

services/core/java/com/android/server/wm/ActivityStarter.java

@@ -1798,7 +1798,7 @@ class ActivityStarter {
         mRootWindowContainer.startPowerModeLaunchIfNeeded(
                 false /* forceSend */, mStartActivity);
 
-        final boolean isTaskSwitch = startedTask != prevTopTask;
+        final boolean isTaskSwitch = startedTask != prevTopTask && !startedTask.isEmbedded();
         mTargetRootTask.startActivityLocked(mStartActivity,
                 topRootTask != null ? topRootTask.getTopNonFinishingActivity() : null, newTask,
                 isTaskSwitch, mOptions, sourceRecord);