Make ShadeControllerImpl use KeyguardViewController

ShadeControllerImpl currently references StatusBarKeyguardViewManager
directly instead of using the interface KeyguardViewController. This
creates dependency injection issues, which can be read in more detail
in b/393883346. Also deletes some dead code.

Fixes: 393883346
Test: quick manual check and presubmits
Flag: EXEMPT no functional changes
Change-Id: I2241294c5da492caa6db1db95c30291d424919f8