Werk #7089: Docker container: Simplified update procedure

The update procedure of the official Check_MK containers was a bit complicated compared to the update procedure on other servers. The root cause for this was that the update always required both, the old and the new versions, while the containers are only allowed to have one version installed. This made it necessary to create an intermediate container for the update.

The werk #7088 made it possible to perform an update without having access to the old version. Once we have this functionality it is now possible to replace one container with a another container. In case the version has changed, the container is performing the update during startup of the new container.

The simplified update procedure can be used for Docker container updates to version 1.6 or newer when the previous version is 1.5.0p13 or newer.

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