Fix to be able to edit seconds in Japanese date/datetime cells

Currently seconds in Japanese date/datetime cells can't be edited.
But i18npool/source/localedata/data/locale.dtd and
offapi/com/sun/star/i18n/NumberFormatIndex.idl say that seconds in
time/datetime cells should be editable. And Japanese users
reported that current behavior is inconvenient.

Also to retain relativity against @formatindex='40', each
[@usage='TIME']/@type are shorten.

For better backward compatibility, @formatindex='55' should be
default format. But since there is implementation limit of
SvNumberFormatter::ImpGenerateFormats, @formatindex>=50 can't
be default one.

These changes are discussed in Japanese ML:
http://listarchives.libreoffice.org/ja/discuss/msg03044.html

Change-Id: Id65125d14183d0e6e61ddb29682e16c2b4cb1f83
Reviewed-on: https://gerrit.libreoffice.org/9705
Reviewed-by: Eike Rathke <erack@redhat.com>
Tested-by: Eike Rathke <erack@redhat.com>