Do not show splash screen icon in the same task by default.

Adjust the check priority when choose solid color splash screen.
Basically lower down the default showing icon condition, and only
show splash screen icon if the activity is launching to a new task.

App launched from Launcher or SystemUI should always request new task,
also since Launcher and SystemUI will specify the launch style, so
there should be no difference.

Most of time SUW won't launch app to new task, so even it is HOME
process, there should not show splash screen icon in the entire
setup sequence.

Bug: 343204515
Bug: 343203529
Flag: EXEMPT bugfix
Test: atest ActivityRecordTests SplashscreenTests
Test: try launch activity with FLAG_ACTIVITY_CLEAR_TASK, verify the
splash screen should choose solid color.

Change-Id: I7230936da1663cea412356d86a745199ac87163d