Bug 28064: (QA follow-up) Remove value from button

Bug 28064: (QA follow-up) Remove value from button

To clarify that the value is not used on buttons that are not submit
type we remove the value entirely.

Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
(cherry picked from commit e77fa64e31cdf026030c4a354bf73e4ee7e2bb14)
Signed-off-by: Fridolin Somers <fridolin.somers@biblibre.com>
(cherry picked from commit c9c0f8c65dc655306af94a2dd890389180e3d5fb)

Signed-off-by: Andrew Fuerste-Henry <andrew@bywatersolutions.com>
(cherry picked from commit 0f6c4892c79a8fb31207eefb46f3c3802f9ecffe)
Signed-off-by: Victor Grousset/tuxayo <victor@tuxayo.net>