[IMP] sale, account, purchase, repair, POS, delivery: shorter fields label

In described Modules, there are some fields label like Unit of measure, Discount,
Ordered Quantity, etc... in views(list,form), report and portal, that are messy
and barely readable when lots of features are installed.

Purpose of the task is to shorter that all fields label to make clean view in
order to make it more readable without getting labels uselessly spread out on
several lines

Related to task #1933746
Closes #31962

Signed-off-by: Thibault Delavallee (tde) <tde@openerp.com>