[CLEANUP] Cleanup \EBT\ExtensionBuilder\Domain\Model\BackendModule

Resolves: #58273
Releases: 6.2
Change-Id: Icd5c6ea01a02a9299993e915c1b58966ba324d1d
Reviewed-on: https://review.typo3.org/29693
Reviewed-by: Nico de Haen
Tested-by: Nico de Haen