message: Only call topn when having_filters don't exist
diff: @@ -2399,7 +2399,7 @@ class DruidDatasource(Model, AuditMixinNullable, Queryable, ImportMixin):
  if len(groupby) == 0:
  del qry['dimensions']
  client.timeseries(**qry)
  - if len(groupby) == 1:
  + if not having_filters and len(groupby) == 1:
  qry['threshold'] = timeseries_limit or 1000
  if row_limit and granularity == 'all':
  qry['threshold'] = row_limit
  