Dsbenchmark: Conflicting modification for test-status on install

This is very similar to CONTROLLER-1552 but the transaction failure cause is different, so opening a new bug.

Benchmark is not a Bugzilla component for Controller project, so opening under Clustering component.

Upon installation of odl-mdsal-benchmark, each member tries to write initial test-status transaction. In very rare cases, two members submit at the same time, leading to "ConflictingModificationAppliedException: Node was created by other transaction".

As this is happening in config-pusher, unhandled OptimisticLockFailedException prevents creation of ModuleIdentifier

which leads to "Configuration Transaction failed on 2PC, server is unhealthy" and a red dot in CSIT. See job console output [0].

[0] https://logs.opendaylight.org/releng/jenkins092/controller-csit-3node-periodic-benchmark-only-carbon/322/console.log.gz