Use DockManager to check whether it's docking or not

Instead of using pulsing reason to verity if it's docking, using
DockManager's API to unbind the check from doze pulsing.

Bug: 140915138, 136070077
Test: atest SystemUITests
Change-Id: I9f52e00042c7c9a665034e094c0744adaa93ef89
8 files changed