Restore _layouts/default.html to original state

The version warning in 1.1 is in _includes/warning.html, not _layouts/default.html.
Reverting the incorrect changes to default.html while keeping the correct fix in warning.html.

Signed-off-by: Claude <noreply@anthropic.com>

Author: kolchfa-aws

_layouts/default.html

@@ -142,10 +142,7 @@ <h1><a href="https://docs.opensearch.org/latest/">Documentation</a></h1>
           {% endif %}
         {% endunless %}
         <div id="main-content" class="main-content" role="main">
-            {% if site.doc_version == "supported" %}
-              <p class="supported-version-warning">You're viewing version {{site.opensearch_major_minor_version}} of the OpenSearch documentation. For the latest version, see the <a href="{% if page.url contains '404' %}{{ site.url }}/latest/about/{% else %}{{ site.url }}/latest{{ page.url }}{% endif %}">current documentation</a>. For information about OpenSearch version maintenance, see <a href="https://opensearch.org/releases.html">Release Schedule and Maintenance Policy</a>.</p>
-            {% elsif site.doc_version == "unsupported" %}
-              <p class="unsupported-version-warning">You're viewing version {{site.opensearch_major_minor_version}} of the OpenSearch documentation. This version is no longer maintained. For the latest version, see the <a href="{% if page.url contains '404' %}{{ site.url }}/latest/about/{% else %}{{ site.url }}/latest{{ page.url }}{% endif %}">current documentation</a>. For information about OpenSearch version maintenance, see <a href="https://opensearch.org/releases.html">Release Schedule and Maintenance Policy</a>.</p>
+          {% include warning.html %}
           {% if site.heading_anchors != false %}
             {% include vendor/anchor_headings.html html=content beforeHeading="true" anchorBody="<svg viewBox=\"0 0 16 16\" aria-hidden=\"true\"><use xlink:href=\"#svg-link\"></use></svg>" anchorClass="anchor-heading" anchorAttrs="aria-labelledby=\"%html_id%\"" %}
           {% else %}