[BUGFIX] Remove validation for field source_path

This patch removes the validation of the source_path field.
It is not possible to validate the input because a RegExp is
allowed for this field which can’t be validated with this checks.

Resolves: #83660
Releases: master
Change-Id: I9420997ba35e3fc312ad2eb4b0a439d56e7b2fe7
Reviewed-on: https://review.typo3.org/55460


Tested-by: TYPO3com <no-reply@typo3.com>
Reviewed-by: Reiner Teubner <rteubner@me.com>
Tested-by: Reiner Teubner <rteubner@me.com>
Reviewed-by: Susanne Moog <susanne.moog@typo3.org>
Tested-by: Susanne Moog <susanne.moog@typo3.org>