Heat is staying in status blocked Missing relation database when
doing an upgrade from stable to next. Missing required data:
database_password. The relation is actually passing heat_password.
Commit 1bdc87f495898be3a9877f0a14528ce48c27f3f0 removed the heat_
prefix. This changes restores the heat_ prefix to allow stable to
next upgrades to work.
Change-Id: Id87afd5eda14eceac6c734867f9f96328c116c79
Closes-Bug: #1571830