[BUGFIX] Correct show configuration in newContentElement wizard

[BUGFIX] Correct show configuration in newContentElement wizard

All elements should be shown if the asterisk is part of the show
configuration. Due to different configuration possibilities it can happen
that the asterisk is not the only value of this configuration.

Resolves: #77877
Releases: master, 7.6, 6.2
Change-Id: I5439f76ec40788cdaed14012e7b83b18e2b56d18
Reviewed-on: https://review.typo3.org/49883
Tested-by: TYPO3com <no-reply@typo3.com>
Reviewed-by: Markus Sommer <markussom@posteo.de>
Tested-by: Markus Sommer <markussom@posteo.de>
Reviewed-by: Nicole Cordes <typo3@cordes.co>
Tested-by: Nicole Cordes <typo3@cordes.co>