Blog updates and enhancements 25Q1

[chalin]

• Rendering support for blog-section content:
  • Blog 2025 section: offer wishes and hope of articles to come #5885 - custom change
  • Blog list layout: display the page title and content google/docsy#2157 - upstreamed
  • Update Docsy - Update Docsy and drop blog layout overrides #5915
• Drop .td-breadcrumbs__single style override once Docsy updated with Hide index-page single breadcrumb google/docsy#2160, which will affect the blog-index page - Update Docsy and drop blog layout overrides #5915
• Drop override that displays the blog-post-is-dated notice once Docsy supports this feature - Update Docsy and drop blog layout overrides #5915
• Drop layouts/blog/baseof.html override once the following lands:
  Breadcrumb for blog pages, and per-page/section config google/docsy#2161 - Update Docsy and drop blog layout overrides #5915
• Create 2025 blog section and adjust redirects #5873
• Track cross-posted blog articles #6329
• ...