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

Resolves: #58274
Releases: 6.2
Change-Id: I39709aad75919b735e527459553bbe2e554d0fe2
Reviewed-on: https://review.typo3.org/29695
Reviewed-by: Nico de Haen
Tested-by: Nico de Haen