ja_JP: Change the offset for Taisho gan-nen from 2 to 1 [BZ #24162]

The offset in era-string format for Taisho gan-nen (1912) is currently
defined as 2, but it should be 1.  So fix it.  "Gan-nen" means the 1st
(origin) year, Taisho started on July 30, 1912.

Reported-by: Morimitsu, Junji <junji.morimitsu@hpe.com>
Reviewed-by: Rafal Luzynski <digitalfreak@lingonborough.com>

ChangeLog:

	[BZ #24162]
	* localedata/locales/ja_JP (LC_TIME): Change the offset for Taisho
	gan-nen from 2 to 1.  Problem reported by Morimitsu, Junji.

(cherry picked from commit 31efface)