Fixed warnings generated by rustc 1.57.0

This CL fixes warnings related to unused fields.  These fields had
previously been considered used because they were read by the Debug
trait, but this behavior changes in the new version of rustc.  These
fields are now temporarily annotated to suppress warnings until it
is determined if they are needed.

Bug: 203802952
Test: Build and boot cuttlefish
Change-Id: Ia314e98d7208e8fa4019c218ae554b0c9afec7db