SystemUI : Fix left swipe when dismissing bouncer

- Only show bouncer when requesting dismiss, which will set the states
for us.
- Also remove duplicate states.
- Ensure we disable edge gesture when showKeyguard is called
- Bail out on showKeyguard if already in keyguard.

CYNGNOS-2872

Change-Id: I6be10923de1590b386c270925654669a8f832cfe
(cherry picked from commit 2cfbb7a3)