Physical keyboard options category is hidden when there is no hardware
keyboard. It's related preferences are hidden in this case. Hence those
preferences shouldn't be searchable.
Bug: 351047456
Test: manually search "bounce keys", "sticky keys" and "slow keys",
they're not searchable when invisible on Accessibility page
Test: atest
Flag: com.android.settings.accessibility.fix_a11y_settings_search
Change-Id: I1eb465dd34e59d856bb1fa7c06bc253971a8c8d0