MHC should ignore paused machines

[yastij]

What steps did you take and what happened:

Currently, MHC ignores paused MHCs/Clusters but not paused machines, this leads to machines being deleted when the pause annotation is removed, which isn't the desired intent.

@fabriziopandini also proposed introducing an MHC-specific annotation to only skip remediation while still keeping objects being reconciled.

cc @CecileRobertMichon @vincepri

What did you expect to happen:

Anything else you would like to add:
[Miscellaneous information that will assist in solving the issue.]

Environment:

• Cluster-api version:
• Minikube/KIND version:
• Kubernetes version: (use kubectl version):
• OS (e.g. from /etc/os-release):

/kind bug

[fabriziopandini]

/milestone v0.4.0
IMO this is a candidate for backporting as well; this is another reason I'm+1 for having a separate annotation to add when the intent is to have MHC temporarily skip remediation on a machine.

[vincepri]

+1 to respect the paused annotation, and let's definitely backport to v0.3.x as well

[yastij]

/assign

[vincepri]

/help
/assign @shysank

[k8s-ci-robot]

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In response to this:

/help
/assign @shysank

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[vincepri]

/priority important-soon

We should also probably backport this change.