Trashed nodes with menu links poison the menu block render cache (max-age=0)

Problem/Motivation

When a node is trashed, its menu_link_content entities are left behind. The TrashEntityTypeManager prevents the trashed node from being loaded, which causes ParamNotConvertedException in AccessManager::checkNamedRoute(). This returns AccessResult::forbidden()->setCacheMaxAge(0).

This max-age=0 bubbles up through the render tree and makes the entire menu block uncacheable. On every page load, Drupal re-runs access checks on all menu links (nearly 1000 in our case), causing 3–4 second page load times.

A single trashed node with a menu link is enough to break the render cache for the entire menu block.

Steps to reproduce

1. Enable the Trash module with node as a trashable entity type.
2. Create a node and add a menu link for it in the main navigation.
3. Trash the node.
4. Clear caches (drush cr).
5. Load any page that displays the main menu block.
6. Check the render cache: the menu block is not cached (max-age=0).
7. Reload the page: it is still slow because the block is re-rendered every time.

Root cause

The call chain is:

1. SystemMenuBlock::build() loads the menu tree and applies the checkAccess manipulator.
2. DefaultMenuLinkTreeManipulators::checkAccess() calls menuLinkCheckAccess() per link.
3. menuLinkCheckAccess() calls AccessManager::checkNamedRoute().
4. checkNamedRoute() calls ParamConverterManager::convert() which tries to load the node.
5. TrashEntityTypeManager::getStorage() returns a storage that filters out trashed entities.
6. EntityConverter cannot load the trashed node and throws ParamNotConvertedException.
7. checkNamedRoute() catches the exception and returns AccessResult::forbidden()->setCacheMaxAge(0).
8. This max-age=0 bubbles up to the menu block render array, making it uncacheable.

Impact

On a production site with ~960 menu links in the main navigation and 12 trashed nodes with menu links, the page load time went from ~100ms (cached) to 3–4 seconds on every request. The issue started as soon as the first node with a menu link was trashed.

Proposed resolution

When a node is trashed, the Trash module should disable or delete the associated menu_link_content entities. The existing MenuLinkContentTrashHandler handles trashing of menu link entities themselves, but there is no handler for the reverse case: a node being trashed while menu links reference it.

Possible approaches:

• In the node trash handler, find and disable all menu_link_content entities that reference the trashed node (and re-enable them on restore).
• Alternatively, make the EntityConverter aware of trashed entities so that the access result is cacheable (e.g., return forbidden with appropriate cache tags instead of max-age=0).

Related issue

#3398777: Custom menu links are not updated when a node is soft-deleted (closed as "works as designed", but the render cache performance impact was not discussed).