`placement-status upgrade check` fails

Description
===========

https://review.openstack.org/#/c/631604/ added a new command to placement:
`placement-status upgrade check`

However, it fails locally logging that it finds no database connection.

$ placement-status upgrade check
Error:
Traceback (most recent call last):
  File "/usr/local/lib/python3.6/dist-packages/oslo_upgradecheck/upgradecheck.py", line 189, in main
    return conf.command.action_fn()
  File "/usr/local/lib/python3.6/dist-packages/oslo_upgradecheck/upgradecheck.py", line 98, in check
    result = func(self)
  File "/opt/stack/placement/placement/cmd/status.py", line 60, in _check_incomplete_consumers
    missing_consumer_count = self._count_missing_consumers(self.ctxt)
  File "/usr/local/lib/python3.6/dist-packages/oslo_db/sqlalchemy/enginefacade.py", line 1011, in wrapper
    with self._transaction_scope(context):
  File "/usr/lib/python3.6/contextlib.py", line 81, in __enter__
    return next(self.gen)
  File "/usr/local/lib/python3.6/dist-packages/oslo_db/sqlalchemy/enginefacade.py", line 1061, in _transaction_scope
    context=context) as resource:
  File "/usr/lib/python3.6/contextlib.py", line 81, in __enter__
    return next(self.gen)
  File "/usr/local/lib/python3.6/dist-packages/oslo_db/sqlalchemy/enginefacade.py", line 659, in _session
    bind=self.connection, mode=self.mode)
  File "/usr/local/lib/python3.6/dist-packages/oslo_db/sqlalchemy/enginefacade.py", line 418, in _create_session
    self._start()
  File "/usr/local/lib/python3.6/dist-packages/oslo_db/sqlalchemy/enginefacade.py", line 510, in _start
    engine_args, maker_args)
  File "/usr/local/lib/python3.6/dist-packages/oslo_db/sqlalchemy/enginefacade.py", line 532, in _setup_for_connection
    "No sql_connection parameter is established")
oslo_db.exception.CantStartEngineError: No sql_connection parameter is established