Issue #3605110 by mably: Webform PDV configuration fields appear on every element/handler edit tab instead of only General

Wraps the handler "Vault consumer" select in a groupable container (with #parents pinned to the flat consumer key) and sets #group to tab_general on the element form "Personal Data Vault" section, so the PDV configuration fields render only on the General edit tab. Adds regression tests for both forms. See the issue summary for the full analysis.