[BUGFIX] Missing clearfix for plugins and persons

Thanks to Robert Vock for the patch

Resolves: #56093
Releases: 6.2

Change-Id: I2083167b13d9c4ff6bcf06b2b4a8176baace762a
Reviewed-on: https://review.typo3.org/28653
Reviewed-by: Nico de Haen
Tested-by: Nico de Haen