Fixing work widgets tab in WidgetsFullSheet.

Currently the work widget matcher matches against all
non-foreground user profiles, due to which the work
tab is incorrectly shown in widgets full screen, when
PS is present.
This was missed in ag/25129268 where a bunch of work
matcher fixes were done.

Flag: ACONFIG com.android.launcher3.Flags.enable_private_space DEVELOPMENT
Bug: 312900122
Test: Launcher3 tests
Change-Id: I80d33e851ea3366dc3897bb1f5cc17fcd6b34520