Fix double counting of margins in keygaurd status bar view

The margin for the status icons was moved to the outer container, but
KeyguardStatusBarView was still putting the margin manually on the
system icon container. This CL removes that extra padding

Test: check keyguard status icon container size in web-hv
Bug: 228928266
Change-Id: I5dd557c5506296532dc7bfb16930ec1b20b0ffdd