Save record fields only required for EventBridge events (#314)

Why these changes are being introduced:
* Saving the entire Record object to the 'event_records' dictionary in-memory
was causing the container to run out-of-memory. This update applies the
solution from #112.

How this addresses that need:
* Only save the fields that are required for the EventBridge details param.

Side effects of this change:
* None

Relevant ticket(s):
* https://mitlibraries.atlassian.net/browse/GDT-323

harvester/harvest/mit.py

@@ -184,23 +184,32 @@ def send_eventbridge_event(self, records: Iterator[Record]) -> Iterator[Record]:
         path = path.removesuffix("/")
 
         # queue EventBridge events
-        event_records: dict[str, Record] = {}
+        event_records: dict[str, dict] = {}
         for record in records:
             if not self.skip_eventbridge_events:
-                event_records[record.identifier] = record
+                record_dict = {
+                    "record_identifier": record.identifier,
+                    "source_record_is_restricted": record.source_record.is_restricted,
+                    "source_record_is_deleted": record.source_record.is_deleted,
+                    "source_metadata_filename": record.source_record.source_metadata_filename,  # noqa: E501
+                    "normalized_metadata_filename": record.source_record.normalized_metadata_filename,  # noqa: E501
+                }
+                event_records[record.identifier] = record_dict
             yield record
 
         # after Records yielded, publish EventBridge events
-        for record in event_records.values():
-            message = f"Record {record.identifier}: sending EventBridge event"
+        for event_record in event_records.values():
+            message = (
+                f"Record {event_record['record_identifier']}: sending EventBridge event"
+            )
             logger.debug(message)
             try:
-                self._prepare_payload_and_send_event(bucket, path, record)
+                self._prepare_payload_and_send_event(bucket, path, event_record)
             except Exception:
                 logger.exception("Error sending EventBridge event")
 
     def _prepare_payload_and_send_event(
-        self, bucket: str, path: str, record: Record
+        self, bucket: str, path: str, record: dict
     ) -> str:
         """Prepare event detail and send event.
 
@@ -221,13 +230,13 @@ def _prepare_payload_and_send_event(
         """
         detail = {
             "bucket": bucket,
-            "identifier": record.identifier,
-            "restricted": json.dumps(record.source_record.is_restricted),
-            "deleted": json.dumps(record.source_record.is_deleted),
+            "identifier": record["record_identifier"],
+            "restricted": json.dumps(record["source_record_is_restricted"]),
+            "deleted": json.dumps(record["source_record_is_deleted"]),
             "objects": [
-                {"Key": f"{path}/{record.source_record.source_metadata_filename}"},
-                {"Key": f"{path}/{record.source_record.normalized_metadata_filename}"},
-                {"Key": f"{path}/{record.identifier}.zip"},
+                {"Key": f"{path}/{record['source_metadata_filename']}"},
+                {"Key": f"{path}/{record['normalized_metadata_filename']}"},
+                {"Key": f"{path}/{record['record_identifier']}.zip"},
             ],
         }
         return EventBridgeClient.send_event(detail=detail)

tests/test_harvest/test_mit_harvester.py

@@ -277,6 +277,7 @@ def test_mit_harvester_send_eventbridge_duplicate_record_sends_one_last_event(
                 ),
             )
         )
+
     with mock.patch.object(
         MITHarvester,
         "_prepare_payload_and_send_event",
@@ -289,7 +290,7 @@ def test_mit_harvester_send_eventbridge_duplicate_record_sends_one_last_event(
         _output_records = list(harvester.send_eventbridge_event(iter(records)))
 
     mock_method.assert_called_once()
-    assert mock_method.mock_calls[0].args[2].source_record.event == "created"
+    assert not mock_method.mock_calls[0].args[2]["source_record_is_deleted"]
 
 
 def test_mit_harvester_send_eventbridge_multiples_records_send_multiple_events(
@@ -341,7 +342,13 @@ def test_mit_harvester_prepare_payload_and_send_event_success(records_for_mit_st
         harvester._prepare_payload_and_send_event(
             "the-bucket",
             "/path/here",
-            record,
+            record={
+                "record_identifier": record.identifier,
+                "source_record_is_restricted": record.source_record.is_restricted,
+                "source_record_is_deleted": record.source_record.is_deleted,
+                "source_metadata_filename": record.source_record.source_metadata_filename,
+                "normalized_metadata_filename": record.source_record.normalized_metadata_filename,  # noqa: E501
+            },
         )
         mocked_send_event.assert_called_with(
             detail={