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

share/timedef/ca_IT.ISO8859-15.src

@@ -1,7 +1,3 @@
-# Warning: Do not edit. This file is automatically generated from the
-# tools in /usr/src/tools/tools/locale. The data is obtained from the
-# CLDR project, obtained from http://cldr.unicode.org/
-# -----------------------------------------------------------------------------
 #
 # Short month names
 gen.
@@ -53,7 +49,7 @@ dissabte
 %H:%M:%S
 #
 # x_fmt
-%Y-%m-%d
+%d/%m/%Y
 #
 # c_fmt
 %a %e %b %X %Y