Before this commit, if we replaced an icon of the showcase snippet
with an image, this image was streched depending on title size (if too
long and on 2 lines). Its because the align-self default value of a
flex item is strech.

task-2447087

closes odoo/odoo#67244

Signed-off-by: Jérémy Kersten (jke) <jke@openerp.com>