Protect updates.xml from bulk sync overwrite

Set protected=true, remove template reference. updates.xml is managed
by the release workflow, not bulk sync — sync was replacing it with
a stub template containing {{EXTENSION_NAME}} placeholders.

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

definitions/default/waas-component.tf

@@ -85,11 +85,11 @@ locals {
       {
         name              = "updates.xml"
         extension         = "xml"
-        description       = "Joomla extension update server manifest — lists releases for Joomla auto-update; must be kept in sync with manifest.xml version"
+        description       = "Joomla extension update server manifest — lists releases for Joomla auto-update; managed by release workflow, never overwritten by sync"
         required          = true
         always_overwrite  = false
+        protected         = true
         audience          = "developer"
-        template          = "templates/joomla/updates.xml.template"
         stub_content      = <<-MOKO_END
         <!--
           Joomla Extension Update Server XML