Incorrect Dynamo query in ` /api/v1/environments/{environment_api_key}/edge-identity-overrides`

[sentry]

Sentry Issue: FLAGSMITH-API-5H1

ClientError: An error occurred (ValidationException) when calling the Query operation: Invalid KeyConditionExpression: KeyConditionExpressions must only contain one condition per key
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  File "edge_api/identities/views.py", line 403, in get_edge_identity_overrides
    items = edge_identity_service.get_edge_identity_overrides(
  File "edge_api/identities/edge_identity_service.py", line 15, in get_edge_identity_overrides
    ddb_environment_v2_wrapper.get_identity_overrides_by_environment_id(
  File "environments/dynamodb/wrappers/environment_wrapper.py", line 81, in get_identity_overrides_by_environment_id
    return list(
  File "environments/dynamodb/wrappers/base.py", line 64, in _iter_all_items
    query_response = response_getter()  # type: ignore[call-arg]