MINOR: Fix default server config in BenchmarkConfigUtils

[mimaison]

Since
ed367cf
when running benchmarks that call createDummyBrokerConfig() we get the
following error:

java.lang.IllegalArgumentException: requirement failed: If process.roles
contains just the 'broker' role, the node id 0 must not be included in
the set of voters controller.quorum.voters=Set(0)

Reviewers: Chia-Ping Tsai chia7712@gmail.com

[chia7712]

IIRC, I ran all the changed benchmarks to ensure every thing worked... but I definitely did something stupid here. My bad!

#21310 (comment)

[mimaison]

No worries! Since it's the only commit that touched BenchmarkConfigUtils I assumed it was the cause but maybe it's not. I did not do a full bisect as it does not really matter.

[chia7712]

Okay, I made sure to actually run ReplicaFetcherThreadBenchmark, CheckpointBench, and PartitionCreationBench this time! Everything looks good. LGTM