PR review for SolrZkClient

[Aman Raj]

Hi team,

Can someone from the Solr community please review this PR - SOLR-17220 - Make 
the SolrZkClient thread as a daemon thread by amanraj2520 · Pull Request #2376 
· apache/solr (github.com)<https://github.com/apache/solr/pull/2376>.

Thanks,
Aman.