[BUGFIX] Changes indentation in new page wizard

On a page without subpages the indentation for
creating a new page below this page was wrong.
This fix changes the indentation in this special case.

Resolves: #72011
Releases: master, 8.7, 7.6
Change-Id: I505a96126ab8cf69ebae32c5a84aa9dbfa59c87f
Reviewed-on: https://review.typo3.org/53696


Reviewed-by: Wolfgang Klinger <wolfgang@wazum.com>
Tested-by: Wolfgang Klinger <wolfgang@wazum.com>
Tested-by: TYPO3com <no-reply@typo3.com>
Reviewed-by: Andreas Fernandez <typo3@scripting-base.de>
Reviewed-by: Joerg Boesche <typo3@joergboesche.de>
Reviewed-by: Susanne Moog <susanne.moog@typo3.org>
Tested-by: Susanne Moog <susanne.moog@typo3.org>