Monitor lizard partitions mount state

Sometimes some of the lizard’s {host,VMs} partitions get remounted read-only.

We should have a check in our Icinga2 infra that reports if that is the case, so that our sysadmins can quickly take care of it, and users don’t notice a service failure.

Related issues

Related to #11866 (closed)

Original created by @bertagaz on 11870 (Redmine)

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