Layout the existing Task to ensure the bounds are updated

An existing Task was started with requested bounds via
ActivityOptions#setLaunchBounds, but the Task bounds was
not the same as the requested bounds.

Bug: 390291971
Test: StartActivityTests#testStartActivityWithLaunchBounds
Flag: com.android.window.flags.fix_layout_existing_task
Change-Id: I3bfc195c89e19c72d1d3f73ac4e00a1f65444e4e