Only enforce max width for non-initial requested display size

For example, the initial size is 1000x2000 and max-width is 800.
When setting 1000x2000, it should clear the override setting
instead of override as 800x1600.

Bug: 274111844
Flag: EXEMPT bugfix
Test: atest DisplayWindowSettingsTests#testSetForcedSize

Change-Id: I1a685111bf6fad9f0fb737e51bb13f5ab25e41b1