Partial revert of "Prepare LightBarController for multi display"

This partially reverts commit 88228a8a.

Reason for revert: b/379344858

Fully reverts the changes in NavigationBar.java, and creates a
"LegacyFactory" that instantiates the dependencies in the same way as
they were being instantiated before.

Fixes: 379344858
Test: atest SystemUITests
Flag: EXEMPT bug fix
(cherry picked from https://googleplex-android-review.googlesource.com/q/commit:63f2de1e68ae22b237181369ef54eceedc49f26e)
Merged-In: Iccb1df6725d6529a8eeff5b0f081b150747e5077
Change-Id: Iccb1df6725d6529a8eeff5b0f081b150747e5077