[TASK] Remove old class files in ext:taskcenter

Remove old class files in ext:taskcenter

Change-Id: Ia998f65eb9c4b4e9b0abe1d5d63b145f36335434
Resolves: #51594
Releases: 6.2
Reviewed-on: https://review.typo3.org/23499
Reviewed-by: Kai Ole Hartwig
Tested-by: Kai Ole Hartwig
Reviewed-by: Christian Kuhn
Tested-by: Christian Kuhn