Don't fit action bar if decorFitsSystemWindows is false

If decorFitsSystemWindows is false, the content view should not fit any
system bars, including action bar. And the content view should get
insets from all the system bars.

Bug: 218827628
Flags: NA
Test: atest ActionBarOverlayLayoutTest
Change-Id: I7cfe6be9033cb4f270176de9b63a3d5d2435832d