FIX: Include lazyYT-container in cooked post HTML (#9870)

FIX: Include lazyYT-container in cooked post HTML (#9870)

This applies the new styles without waiting for the JS to run.

diff --git a/plugins/lazy-yt/plugin.rb b/plugins/lazy-yt/plugin.rb
index 4f5517c..06b25ce 100644
--- a/plugins/lazy-yt/plugin.rb
+++ b/plugins/lazy-yt/plugin.rb
@@ -32,7 +32,7 @@ class Onebox::Engine::YoutubeOnebox
       escaped_title = ERB::Util.html_escape(video_title)
 
       <<~EOF
-      <div class="onebox lazyYT"
+      <div class="onebox lazyYT lazyYT-container"
            data-youtube-id="#{video_id}"
            data-youtube-title="#{escaped_title}"
            data-width="#{video_width}"

GitHub sha: 97909378

This commit appears in #9870 which was merged by riking.