Revert "[TASK] Rebuild the calcAge functionality"

This change was considered to need some more work during
merge post review:
* 6.2 version adds not allowed deprecations to a released branch
* It adds two arbitrary (public) constants CEIL and FLOOR
* Method names need improvement
* Violation of single responsibility
* The static utility class has dependencies
* The patch adds another "always loaded" file to main bootstrap
* Undocumented (minor) breaking changes
* (Minor) code style issues

Reverted: #20016
Releases: 6.3, 6.2

This reverts commit 4c52cb3cfe4f6819a29f1daa064859affe23989d
Change-Id: I6dff8aaa8bf8cfdb80cca56c9c967f2a2ea6fb52
Reviewed-on: https://review.typo3.org/31237
Reviewed-by: Christian Kuhn
Tested-by: Christian Kuhn