[BUGFIX] Can not expand new collapsed IRRE record with RTE field

Problem: You can not expand newly created, collapsed IRRE records
which have a RTE field.
Solution: Adapt RTE to modified way of hidding IRRE nested element.

Revolves: #44617
Releases: 6.0, 6.1, 6.2
Change-Id: I262056af820054a168e695b01270463d56ea7b18
Reviewed-on: https://review.typo3.org/20871
Reviewed-by: Stanislas Rolland
Tested-by: Stanislas Rolland