[BUGFIX] Remove table prefix check in CONTENT

Records of sys_category could not be rendered with
the content object CONTENT, because only tables
prefixed with pages,tt,fe,tx,ttx,user and static are
allowed. Nowadays this limitation isn't practical
anymore, because other tables don't matching the
prefix will follow.

Resolves: #44961
Releases: 6.2
Change-Id: Iab6671edff8d6f3558ca4a56caa4dae797c66187
Reviewed-on: https://review.typo3.org/25316
Reviewed-by: Helmut Hummel
Reviewed-by: Ernesto Baschny
Reviewed-by: Georg Ringer
Tested-by: Georg Ringer