[!!!][TASK] Remove import of PHP files of admins from impexp

The functionality, which was only allowed for admins, does not
consider FAL restrictions. In order to be consistent with FAL, this
is removed.

Resolves: #88681
Releases: master
Change-Id: I7a42539b5391af7d730deabffbe638a2ceed1a05
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/61221


Tested-by: Andreas Fernandez <a.fernandez@scripting-base.de>
Tested-by: TYPO3com <noreply@typo3.com>
Tested-by: Oliver Hader <oliver.hader@typo3.org>
Reviewed-by: Andreas Fernandez <a.fernandez@scripting-base.de>
Reviewed-by: Oliver Hader <oliver.hader@typo3.org>