Revert "Fix invalid HTML"

This reverts commit d45f1dc.

The change introduced a regression when removing a project from the
manage user page, because the "Remove" button is generated as an HTML
form (via print_project_user_list -> html_button() functions). Since
forms cannot be nested, the parent form's action (manage_user_proj_add.php)
gets triggered instead of the expected one (manage_user_proj_delete.php).

Fixes #28106

manage_user_edit_page.php

@@ -319,7 +319,6 @@
 <div class="widget-body">
 <div class="widget-main no-padding">
 <div class="form-container">
-<form id="manage-user-project-add-form" method="post" action="manage_user_proj_add.php">
 <div class="table-responsive">
 	<table class="table table-bordered table-condensed table-striped">
         <tr>
@@ -328,6 +327,7 @@
             </td>
             <td><?php print_project_user_list( $t_user['id'] ) ?></td>
         </tr>
+        <form id="manage-user-project-add-form" method="post" action="manage_user_proj_add.php">
         <fieldset>
             <?php echo form_security_field( 'manage_user_proj_add' ) ?>
             <input type="hidden" name="user_id" value="<?php echo $t_user['id'] ?>" />
@@ -357,9 +357,9 @@
             </td>
         </tr>
         </fieldset>
+        </form>
 	</table>
 </div>
-</form>
 </div>
 </div>
 </div>