[forms] Fix HTableFormRenderer _render_fields method behavior when display_label is False.
Indeed, now the extra <tr><th>...</th></tr> are not inserted anymore unless
display_label is True.
Closes #3811325.
Document: cubicweb-doc
Title: CubicWeb documentation
Author: Logilab
Abstract: Some base documentation for CubicWeb users and developpers
Section: Apps/Programming
Format: HTML
Index: /usr/share/doc/cubicweb-documentation/html/index.html
Files: /usr/share/doc/cubicweb-documentation/html/*