[Image2, ACF] Content of figcaption remain once the tag is stripped out in a widget

[Olek Nowodziński]

Problem: If user explicitly disallows figcaption in ACF, figures are upcasted but the contents of (just stripped out) figcaption remain as a plain, non-editable paragraph withing widget's body.

Expected: Once figcaption is disallowed, its contents should be removed from the widget. Such widget should be upcasted either to an inline widget or a block widget without caption (to be decided).