Stop reporting the duration including sleep for background DexOpt

It is not needed anymore becaus the job scheduler holds a wake
lock, so this duration is always the same as duration_ms.

Bug: 255759883
Test: atest BackgroundDexOptServiceUnitTest
Merged-In: I10313e007b987569dd67b0ab0867a52745dd6a8b
Change-Id: I0461f4f65f4c0b9a4368e3e0f83050de5b6ba141