Bump up the helix version to 0.9.8
Helix 0.9.8 includes the critical bug fix that would reduce
the load to ZK.
More detailed release note can be found at the following:
<!-- Configuration for unit/integration tests section 1 of 3 (properties) ENDS HERE.-->
<avro.version>1.7.6</avro.version>
<parquet.version>1.8.0</parquet.version>
- <helix.version>0.9.7</helix.version>
+ <helix.version>0.9.8</helix.version>
<zkclient.version>0.7</zkclient.version>
<jackson.version>2.9.8</jackson.version>
<async-http-client.version>1.9.21</async-http-client.version>
