XD-1983 NodeExistException on ModuleMetadata write

- Ignore ZK `NodeExistsException` on writing module metadata as this
is likely to happen when the container disconnects and reconnects
but the admin leader was not available to handle the container
departure event.
  - In this case, upon container disconnect the modules on that
container get undeployed and when the container reconnects
the `DeploymentListener` makes sure to deploy the same modules
except the fact that the ZK paths for the deployment and module
metadata already exists.
These changes should be fine. Initially I was thinking the sequence number would enable us to be more specific on the module, but I realize the container can have only one module of a given label so we are fine here.
Thanks for making the changes while merging.