Islandora generates Link headers for non-repository content

[kayakr]

Ran into an issue where the number of HTML Link headers exceeds the default limit for headers in Varnish http_max_hdr: 64 resulting in a Varnish 503 on specific nodes that have a high number of related entities (via an entity reference field). We're looking to boost the number of headers varnish will handle, but I also found islandora/src/EventSubscriber/NodeLinkHeaderSubscriber.php generates link headers even for content types that are not islandora objects.

IMO, it would be good for NodeLinkHeaderSubscriber to have a setting to limit its action to specific bundles, e.g. islandora_object and others as specifically identified.