[ENH][UX] Trackers: User Selector Field: Improve UX for picking a user when it is set to Multiple selection (filterable by group)

I tried to go to the Url address that gary used and so I went to the mandatory_categorization_check page on which I did a direct test to better see the error and then inspects it with the DOM of the firefox browser and I could test some value on the line from which to concern the problem.

The best solution I could test was to change the class values where the value "A category is mandatory" was taken over, which gives us that :

{tr}A category is mandatory{/tr}

.

As I had to do it locally for better tests, so I found a solution to do it by temporarily eliminating the {if $category_needed eq'y'} values {remarksbox type='Warning' title="{tr}Warning{/tr}"} and {/remarksbox} {/if} Who surrounds the line

{tr}A category is mandatory{/tr}

to see the elements without going through any condition. After all these changes I still found that wherever the warring type was found "{remarksbox type='Warning' title="{tr}Warning{/tr}"}" the same errors are repeated for (A category is mandatory, A contribution is mandatory, An edit summary is mandatory) and this could cause problems along the way I also allowed myself to change all these values that could return in particular in the files (tamplates/tiki-edit_blog.tpl, tamplates/tiki-editpage.tpl and tamplates/tiki-galleries.tpl).