Containerized mongodb, disable by default, fix upgrade

Containerized mongodb, disable by default, fix upgrade

This change removes the entry to containerise docker by default
because it should now be disabled since the change
Id2e6550fb7c319fc52469644ea022cf35757e0ce.

Removing the entry means the default mapping to mongodb-disabled.yaml
takes effect.

This change also modifies the upgrade_tasks so that the mongod service
is only disabled when the service exists. There appears to be upgrade
scenarios which fail because mongodb was never installed in the first
place.

Change-Id: Ie09ce2a52128eef157e4d768c1c4776fc49f2324
Closes-Bug: #1715031
(cherry picked from commit cb81cbe3b5f3887f5d690c590e52b728f74d43c3)