[web] prevent undesired dragging of an image in the color-picker (#17433)

GitOrigin-RevId: d02892a0f7cf473de4db9a9ca3990b8f473195cf

services/web/frontend/stylesheets/app/project-list-react.less

@@ -971,6 +971,7 @@
 
   .custom-picker {
     position: absolute;
+    user-select: none;
 
     @media (max-width: @screen-xs-max) {
       top: 56px;