Force small clock on small landscape lockscreen (except AOD)

- small clock is now used on lockscreen when: on small landscape screens, AOD is not visible, and flag LOCKSCREEN_ENABLE_LANDSCAPE is enabled.

This is a required feature for landscape lockscreen for small screens

Guarded by flag "lockscreen.enable_landscape" (b/293252410)

Added tests to ensure only small clock is used when the flag is on, screen is small, and screen is landscape.

Bug: 296571001
Bug: 293252410

Test: NotificationPanelViewControllerTest
Change-Id: Ic355ebbb4d175386f525d7b7ef492018199652ef