[Issue 3498] exclude attachments from search response (#3531)

## Summary
Fixes #{[3498](#3498)}

### Time to review: __5 mins__

## Changes proposed
Modified the search method of our opensearch client to pass through an
optional excludes param
Modified our search API to set the attachments field to be excluded

---------

Co-authored-by: nava-platform-bot <[email protected]>

api/src/adapters/search/opensearch_client.py

@@ -216,11 +216,14 @@ def search(
         search_query: dict,
         include_scores: bool = True,
         params: dict | None = None,
+        excludes: list[str] | None = None,
     ) -> SearchResponse:
         if params is None:
             params = {}
 
-        response = self._client.search(index=index_name, body=search_query, params=params)
+        response = self._client.search(
+            index=index_name, body=search_query, params=params, _source_excludes=excludes
+        )
         return SearchResponse.from_opensearch_response(response, include_scores)
 
     def scroll(

api/src/services/opportunities_v1/search_opportunities.py

@@ -180,7 +180,7 @@ def search_opportunities(
         "Querying search index alias %s", index_alias, extra={"search_index_alias": index_alias}
     )
 
-    response = search_client.search(index_alias, search_request)
+    response = search_client.search(index_alias, search_request, excludes=["attachments"])
 
     pagination_info = PaginationInfo(
         page_offset=search_params.pagination.page_offset,