Fix lock pattern is truncated during SUW in folded state

Remove the bottom margin of the header view.

Bug: 285290323
Test: 1. Go through SUW
      2. Select lock pattern
      3. Check if UI truncated
Test: m RunSettingsRoboTests ROBOTEST_FILTER=
      com.android.settings.password.SetupChooseLockPatternTest
Change-Id: I48ac3d897e6b876bd7a1c325cc4a5e797e140da2