[etwist] use more specific REQUEST_ENTITY_TOO_LARGE instead of BAD_REQUEST
When a request body exceeds the configured limit, return 413 to the
client instead of a generic 400.
for table, column in [
('transactions', 'tx_time'),
('tx_entity_actions', 'tx_uuid'),
('tx_relation_actions', 'tx_uuid')]:
repo.system_source.create_index(session, table, column)
commit()