Do not reset category select after adding a value

Users often need to add multiple fields under the same category, so
resetting the selection disrupts their workflow. Additionally, the previous
reset approach did not properly update TomSelect's state, causing confusion
as the current category appeared to remain selected.

Fixes: I#38097

Author: sunnavy

share/html/Admin/Elements/AddCustomFieldValue

@@ -119,7 +119,6 @@ jQuery( function() {
                 jQuery('input[name=CustomField-<% $CustomField->id %>-Value-new-SortOrder]').val(''),
                 jQuery('input[name=CustomField-<% $CustomField->id %>-Value-new-Name]').val('').focus(),
                 jQuery('input[name=CustomField-<% $CustomField->id %>-Value-new-Description]').val(''),
-                jQuery('[name=CustomField-<% $CustomField->id %>-Value-new-Category]').val('');
                 initializeSelectElements(document.querySelector('div.edit_custom_field_values'));
             }
             else {