Ensure header view expected height accounts for tabs.

This was already handled except for the case where there were no
predicted apps and no all apps divider, i.e. suggested apps are
disabled and a work profile is added (so tabs show instead of the
divider).

Why did the other cases work? Predicted apps and the divider are
FloatingHeaderRows which call FloatingHeaderView#onHeightUpdated
whenever they are updated (triggering updateExpectedHeight()).

And why did this sometimes "fix itself" until a reboot? When the
search bar is tapped, the search transition causes the expected
height to be updated. So that is my guess.

The key to this change is to wait to update the expected height
until after we have defined mTabsHidden during setup(). It is
normal for the header to be initialized without tabs and then
updated to show the tabs when the work apps are available. So
this was previously incorrectly using mTabsHidden=true for the
calculations.

Fix: 245516031
Test: Manual (force stop launcher and verify tabs scroll correctly)
Flag: NA
Change-Id: Ifcc2f39649c5494b5f3ebefc1cdddfbefbe5d9a0