[BUGFIX] Category fields are not available in Functional Tests

The category fields are defined dynamically and added to the
extension table configuration. Since the database definitions
are created before modifying this configuration, the category
fields are not available in Functional Tests.

Resolves: #55560
Releases: 6.2
Change-Id: Ie59e544309184d475428bc298f126c2776b4b5e7
Reviewed-on: https://review.typo3.org/27238
Reviewed-by: Anja Leichsenring
Tested-by: Anja Leichsenring
Reviewed-by: Christian Kuhn
Reviewed-by: Oliver Hader
Tested-by: Oliver Hader