Fix a typo.

templates/solr-default.j2

@@ -61,7 +61,7 @@ ZK_HOST="{{ solr_zk_hosts }}"
 # Set the ZooKeeper client timeout (for SolrCloud mode)
 ZK_CLIENT_TIMEOUT="{{ solr_zk_timeout }}"
 
-{% if solr_mode == solrcloud %}
+{% if solr_mode == "solrcloud" %}
 # By default the start script uses "localhost"; override the hostname here
 # for production SolrCloud environments to control the hostname exposed to cluster state
 SOLR_HOST="{{ solr_host_address }}"