Revert "config: Opt-in for Go-variant of SystemUI on Go-enabled targets"

This reverts commit 303692b9.

Turns out that ThemePicker force closes while using SystemUIGo.
Issue already reported: https://issuetracker.google.com/issues/303280734

Change-Id: I630328df7144c04159f746d3efe44ccaa64106bf