Fix workFAB alignment.

The calculation to find how much the FAB should shift is outdated as using the
method from deviceProfile#getAllAppsIconStartMargin() gives a better value.

bug:332761814
Test manually:
after LTR expanded:https://drive.google.com/file/d/1NZQW0CF9VFZBoM3673LFiUknqW2nf4r8/view?usp=sharing
after LTR collapsed: https://drive.google.com/file/d/1NRpdTuYQntSs5-yeRL1fJIJy2ETDOYLM/view?usp=sharing
after RTL collapsed: https://drive.google.com/file/d/1NE51MIsS5Fk0DwAuzCehEQzTa42OGj_o/view?usp=sharing
after RTL expanded: https://drive.google.com/file/d/1NPgiPfzw3DOa_xbB_TtlwK-G1Y5WCi53/view?usp=sharing
Flag:None

Change-Id: I07579635d6176553d27497cb73b81799648fb014