Default maintenance_mode value to false if not explicitly set
What does this MR do?
This MR set maintenance_mode to false by default, if the value was not already set.
A check was introduced in !50425 (merged) that fails if no value has been set for maintenance_mode application setting.
In 13.8 this check was behind a feature flag, whereas in 13.9 the feature flag was removed.
This fixes #321734 (closed)
Screenshots (strongly suggested)
Does this MR meet the acceptance criteria?
Conformity
Edited by Peter Leitzen