Revert "[soong] new field in Android.bp to request APK signing V4"

This reverts commit 17d69e34.

Reason for revert: This new field is not useful without dependencies in aosp

Test: builds
Change-Id: I87bd820cd6dbc5274ce3d28c4578381718aa805d
Merged-In: I70d6f7dc751510311b03e245b2189a76b395a49c