Search: clean up Javadoc in search strategy interfaces and SearchSecurityDecorator #4200

[fractal3000]

Minor Javadoc-only cleanup of classes introduced in #4200. No behavior or API changes.

• OpenSearchSearchStrategy — fix broken {@link} tag ({link @searchstrategy}) that produced a Javadoc warning, and replace the imprecise description.
• ElasticsearchSearchStrategy — replace the imprecise "based on the provided search context" wording (the context is the SearchRequestContext argument of the inherited configureRequest, not something the interface provides).
• SearchSecurityDecorator — replace the inaccurate "Decorates CurrentUserSecurityFacade" description (the class decorates nothing) with an accurate one: entity- and attribute-level read permission checks, delegating to SecureOperations / PolicyStore.