KeyguardViewMediator: Play lock screen sound sooner

When the screen is locked, there is a long pause before the lock
sound actually plays.

This makes that sound happen much sooner.

Also modified Lock.ogg slightly to remove the initial silence.

Change-Id: Iede7a5d22291d1ada98800d2b380c255547df61d
Merge "KeyguardViewMediator: Play lock screen sound sooner" into jb-mr2