Move enable_taskbar_connected_displays to lse_desktop_experiences

Removing launcher flag for taskbar in secondary display and adding it to lse_desktop_experiences.

Test: m
Bug: 393398093
Bug: 383634014
Flag: com.android.window.flags.enable_taskbar_connected_displays
Change-Id: Ia73f31346eb1b3bd273ecb7801eb1264d92e6863