Limit concurrency on machines updated in parallel

[velddev]

Description

It seems like if there's a ".server will be updated in-place" terraform action, it will often try to do all of them in parallel. Sometimes this can cause a restart which causes longhorn to mark all volumes as tainted.

[mysticaltech]

@velddev Interesting, thanks for pointing that out. If you found a fix, PR welcome. @kube-hetzner/core FYI on the above.

[mysticaltech]

Normally the default kured_options are now better and will not allow this to happen, but let me know if it still happens to you in a new issue.