Revert r315571 for share/timedef/ca_IT.ISO8859-15.src, ca_IT is Catalan
in Italy, and is not related to Canada.

While here, remove the header as we do NOT currently use CLDR data to
generate timedef, and it's misleading.

PR: 225855
Reviewed by: bapt
Approved by: re (gjb), kib (mentor)
Differential Revision: https://reviews.freebsd.org/D17551