Remove RefereeLevel.ordering now inherits_from covers the same need

A separate manually-kept number for "which tier is higher" is
redundant now that the inheritance chain already expresses it, and
risked drifting out of sync with it. Levels list/sort by name only.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01ECGMEwrc2k4D8VQuwjstj9

management/templates/management/referee_level_list.html

@@ -15,7 +15,6 @@
         <table class="table">
             <thead>
                 <tr>
-                    <th>{% trans "Ordering" %}</th>
                     <th>{% trans "Name" %}</th>
                     <th>{% trans "Inherits from" %}</th>
                     <th>{% trans "Qualifies for" %}</th>
@@ -25,7 +24,6 @@
             <tbody>
                 {% for level in levels %}
                     <tr>
-                        <td class="font-mono text-muted">{{ level.ordering }}</td>
                         <td class="font-semibold text-ink">{{ level.name }}</td>
                         <td>
                             {% if level.inherits_from %}
@@ -52,7 +50,7 @@
                     </tr>
                 {% empty %}
                     <tr>
-                        <td colspan="5" class="text-center text-muted">{% trans "No referee levels yet." %}</td>
+                        <td colspan="4" class="text-center text-muted">{% trans "No referee levels yet." %}</td>
                     </tr>
                 {% endfor %}
             </tbody>