chore: ElasticSearch - remove legacy filters elasticsearch (#1078)

* Remove legacy filter support

* Improve error message

* Error msg fmt

integrations/elasticsearch/src/haystack_integrations/document_stores/elasticsearch/document_store.py

@@ -12,7 +12,6 @@
 from haystack.dataclasses import Document
 from haystack.document_stores.errors import DocumentStoreError, DuplicateDocumentError
 from haystack.document_stores.types import DuplicatePolicy
-from haystack.utils.filters import convert
 from haystack.version import __version__ as haystack_version
 
 from elasticsearch import Elasticsearch, helpers  # type: ignore[import-not-found]
@@ -224,7 +223,8 @@ def filter_documents(self, filters: Optional[Dict[str, Any]] = None) -> List[Doc
         :returns: List of `Document`s that match the filters.
         """
         if filters and "operator" not in filters and "conditions" not in filters:
-            filters = convert(filters)
+            msg = "Invalid filter syntax. See https://docs.haystack.deepset.ai/docs/metadata-filtering for details."
+            raise ValueError(msg)
 
         query = {"bool": {"filter": _normalize_filters(filters)}} if filters else None
         documents = self._search_documents(query=query)