Prevent setNodesAvailable to be called for not-yet-available nodes (#3096)

* Prevent setNodesAvailable to be called for not-yet-available nodes

- factorize allNodes.put calls in a single method RMCore#makeNodeAvailable that is accessible from the node source and whose returned future is waited on on the node source side, to wait for the node to be added in the map.
- make allNodes map a ConcurrentHashMap because of its access in ImmediateService (in setNodesAvailable)
- in case of recovery, wait for the RM to have its initActivity finished before letting 'setNodesAvailable' (immediate service) proceed