## Problem/Motivation `\Drupal\canvas\ShapeMatcher\PropSourceSuggester::isConsideredIrrelevant()` filters out entity base fields that are never meaningful to offer as prop sources (for example `default_langcode`, `revision_default` and `revision_log_message`). When one of a content entity type's bundles is translatable, the `content_translation` module adds two fixed-name bookkeeping base fields to that entity type: `content_translation_source` and `content_translation_outdated`. These hold internal translation metadata and are never meaningful to display, but `isConsideredIrrelevant()` did not exclude them, so they were offered as prop source suggestions. This surfaced while reviewing [!1289](https://git.drupalcode.org/project/canvas/-/merge_requests/1289) (#3591669), which added the sibling heuristic `ApiUiContentEntityReferenceControllers::isConsideredIrrelevant()` for the content-entity-reference picker and already excludes these two fields. In [a review thread](https://git.drupalcode.org/project/canvas/-/merge_requests/1289#note_1420519), @wimleers asked whether they should be added to `PropSourceSuggester::isConsideredIrrelevant()` too. That was deferred to this follow-up. ## Proposed resolution Add `content_translation_source` and `content_translation_outdated` to the generic heuristics in `PropSourceSuggester::isConsideredIrrelevant()`. ## Remaining tasks - [x] Exclude both fields in `PropSourceSuggester::isConsideredIrrelevant()`. - [x] Add test coverage to `PropSourceSuggesterTest`.