[flexiglass] Removes dependency on ComposeLockscreen

The ComposeLockscreen flag will not be rolling out without Flexiglass,
so removing it to simplify things.

Bug: 283121968
Fix: 360099862
Test: ran with flexiglass on and off - unlocked and relocked the device
Flag: NONE this is a flag changing CL
Change-Id: I6e19c2061edf729e9bc61daf9d8629a3014dc6b2