The property assignment operators' tooltips were never actually
translated when they were constructed dynamically from the description
in the prop's RNA.
This was visible when using such operators in menus (example I found
was the Marker Settings, Shift + E in the Movie Clip Editor).
"%s: %s" is already extracted elsewhere, might as well use it.
Reviewed By: mont29
Differential Revision: https://developer.blender.org/D16439
9795f2645c