Re-introduce concurrent MessageQueue in SystemUI

The underlying issue was addressed in a previous patch.
The disabling of concurrent MQ for SystemUI was made on main temporarily
in the service of cherrypick aosp/3722310.

Bug: 436941592
Bug: 436942235
Flag: build.RELEASE_PACKAGE_MESSAGEQUEUE_IMPLEMENTATION
Change-Id: I785a9b944a508b0b8551aa5baadc05b3344d3d5c