Send an empty payload if a cluster was not found

[fabriziosestito]

This PR sends an empty payload if a cluster was not found, instead of returning from the discovery loop.
This is useful in the delta deregistration to remove a host from a cluster if previously it was part of it.

[arbulu89]

A little change request

[arbulu89]

@fabriziosestito As talked offline, with the current change this is the payload that is generated:

{"agent_id":"xxx","discovery_type":"ha_cluster_discovery","payload":{"Cib":{"Configuration":{"CrmConfig":{"ClusterProperties":null},"Nodes":null,"Resources":{"Primitives":null,"Masters":null,"Clones":null,"Groups":null},"Constraints":{"RscLocations":null}}},"Crmmon":{"Version":"","Summary":{"Nodes":{"Number":0},"LastChange":{"Time":""},"Resources":{"Number":0,"Disabled":0,"Blocked":0},"ClusterOptions":{"StonithEnabled":false}},"Nodes":null,"NodeAttributes":{"Nodes":null},"NodeHistory":{"Nodes":null},"Resources":null,"Clones":null,"Groups":null},"SBD":{"Devices":null,"Config":null},"Id":"","Name":"cib-bootstrap-options-cluster-name","DC":false,"Provider":""}}

I think the cluster variable is not nil in this case.

[arbulu89]

Good!
Now we have:

{"agent_id":"xxx","discovery_type":"ha_cluster_discovery","payload":null}

If sending null in the payload is good enough for the backend (you might know more on that than me hehe), the code works as expected

[arbulu89]

Why have you changed the order of the things here?
Was something wrong?
Or is it simply to avoid the declaration of a not needed var?

[fabriziosestito]

Or is it simply to avoid the declaration of a not needed var?

this