[TASK] Hide "Group by page" if only one page is shown in EXT:belog

It is unnecessary to show the "Group by page" checkbox if "This page" is
selected in the "Depth" dropdown.
Thus, the checkbox is hidden in that case.

Resolves: #83896
Releases: master, 8.7
Change-Id: Idd3e0252c6bb06d2442ed4db95056e1e6d292c6c
Reviewed-on: https://review.typo3.org/55718


Reviewed-by: Mathias Schreiber <mathias.schreiber@typo3.com>
Tested-by: Mathias Schreiber <mathias.schreiber@typo3.com>
Tested-by: TYPO3com <no-reply@typo3.com>
Reviewed-by: Stefan Neufeind <typo3.neufeind@speedpartner.de>
Tested-by: Stefan Neufeind <typo3.neufeind@speedpartner.de>