Bug 8168: (follow-up) Use semicolon as default CSV delimiter

Bug 8168: (follow-up) Use semicolon as default CSV delimiter

installer/data/mysql/sysprefs.sql has semicolon as default.
This fixes both instances to use the same fallback value.

It also prevents CSV header info from being included in non-CSV messages.

Signed-off-by: wajasu <matted-34813@mypacks.net>
Signed-off-by: Jonathan Druart <jonathan.druart@biblibre.com>
Signed-off-by: Galen Charlton <gmc@esilibrary.com>
(cherry picked from commit 7408fa5d7087fad5c8f15b742b9624cbfe652a61)
Signed-off-by: Fridolin Somers <fridolin.somers@biblibre.com>