[BUGFIX] Don't show new button when adding a new record

As there is no "pid" available, the new button on new
records should not be shown.

Resolves: #87721
Releases: master, 9.5
Change-Id: Ie3521882e38f031d3362de841351b058faed9521
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/60506


Tested-by: TYPO3com <noreply@typo3.com>
Tested-by: Josef Glatz <josefglatz@gmail.com>
Tested-by: Susanne Moog <look@susi.dev>
Reviewed-by: Josef Glatz <josefglatz@gmail.com>
Reviewed-by: Susanne Moog <look@susi.dev>