Adjusting paddings in ShadeHeader to allow for hover state

This change is mostly about rearranging paddings and resizing so that in large screen, single line header, border of the shade_header_system_icons is aligned with desired hover state indicator.
There should be no visual changes on handheld.

Bug: 283800652
Bug: 249859409
Test: checking lack of visual changes on small/large screen
Change-Id: I59418bd8280c7e13f4429457cc516aab1b0c3312