Only clear bounds and windowing mode for standard

When we switch between desktop and focused modes, we clear bounds and
reset windowing mode for all tasks.
Make sure this affects only tasks that have activity type set to
ACTIVITY_TYPE_STANDARD. This ensures we don't clear bounds or reset
windowing mode for launcher or split screen stages etc.

Bug: 244348395
Test: atest ShellTaskOrganizerTests
Change-Id: Iaf84cb2733a6ffa93c267cb8c716e7c0eb7ca13f