fix(helpdesk): replace description column with category in team ticket table

Description is not available on PBI_LV_Tickets. Show Category_1_Code
as its own 'Category' column instead of misusing it as description.
Remove unused ticket-desc CSS class.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

modules/helpdesk/pages/helpdesk/team/index(default).phtml

@@ -26,7 +26,7 @@ $periodLabels = [
      data-debitor-base-url="<?php e(lurl('helpdesk/debitor/')); ?>"
      data-label-ticket="<?php e(t('Ticket')); ?>"
      data-label-customer="<?php e(t('Debtor')); ?>"
-     data-label-description="<?php e(t('Description')); ?>"
+     data-label-category="<?php e(t('Category')); ?>"
      data-label-last-activity="<?php e(t('Last activity')); ?>"
 >
   <section>