✨(backend) Index deleted documents

Add SEARCH_INDEXER_COUNTDOWN as configurable setting.
Make the search backend creation simplier (only 'get_document_indexer' now).
Allow indexation of deleted documents.

Signed-off-by: Fabre Florian <ffabre@hybird.org>

src/backend/core/signals.py

@@ -9,7 +9,6 @@ from django.db.models import signals
 from django.dispatch import receiver
 
 from . import models
-from .services.search_indexers import default_document_indexer
 from .tasks.find import trigger_document_indexer
 
 
@@ -20,8 +19,7 @@ def document_post_save(sender, instance, **kwargs):  # pylint: disable=unused-ar
     Note : Within the transaction we can have an empty content and a serialization
     error.
     """
-    if default_document_indexer() is not None:
-        transaction.on_commit(partial(trigger_document_indexer, instance))
+    transaction.on_commit(partial(trigger_document_indexer, instance))
 
 
 @receiver(signals.post_save, sender=models.DocumentAccess)
@@ -29,5 +27,5 @@ def document_access_post_save(sender, instance, created, **kwargs):  # pylint: d
     """
     Asynchronous call to the document indexer at the end of the transaction.
     """
-    if not created and default_document_indexer() is not None:
+    if not created:
         transaction.on_commit(partial(trigger_document_indexer, instance.document))