Remove the last of the ResolvUtil uses

This is the completion of cleanup work started in aosp/674269.
Consequently, also remove ResolvUtil.

Test: as follows
    - built, flashed, booted
    - runtest frameworks-net passes
    - presubmit
Bug: 64133961
Bug: 72345192
Bug: 73872000
Bug: 78548486
Change-Id: I980f8a9b67f3f06f2d97a60f8e58e92c36316d40