Rename FIRST_SDK_INT to DEVICE_INITIAL_SDK_INT

As API review feedback, rename Build#VERSION#FIRST_SDK_INT to
Build#VERSION#DEVICE_INITIAL_SDK_INT. As well as update all usage
in frameworks and tests.

Bug: 184735771
Test: m
Change-Id: I72660959cb4e638a8e80fcf2f4e96ea172969f44