Fix default path for bwc index
Fix default path for bwc index

Original commit: elastic/x-pack-elasticsearch@72bcf992f4cdf45885cee57ccbc7628dc753b3d4

gingerwizard/elasticsearch,GlenRSmith/elasticsearch,uschindler/elasticsearch,uschindler/elasticsearch,GlenRSmith/elasticsearch,robin13/elasticsearch,GlenRSmith/elasticsearch,strapdata/elassandra,HonzaKral/elasticsearch,GlenRSmith/elasticsearch,coding0011/elasticsearch,GlenRSmith/elasticsearch,gingerwizard/elasticsearch,gingerwizard/elasticsearch,nknize/elasticsearch,strapdata/elassandra,scorpionvicky/elasticsearch,coding0011/elasticsearch,strapdata/elassandra,HonzaKral/elasticsearch,robin13/elasticsearch,uschindler/elasticsearch,gfyoung/elasticsearch,nknize/elasticsearch,scorpionvicky/elasticsearch,robin13/elasticsearch,strapdata/elassandra,gingerwizard/elasticsearch,robin13/elasticsearch,strapdata/elassandra,gfyoung/elasticsearch,uschindler/elasticsearch,gfyoung/elasticsearch,coding0011/elasticsearch,coding0011/elasticsearch,nknize/elasticsearch,coding0011/elasticsearch,vroyer/elassandra,scorpionvicky/elasticsearch,HonzaKral/elasticsearch,HonzaKral/elasticsearch,nknize/elasticsearch,vroyer/elassandra,vroyer/elassandra,scorpionvicky/elasticsearch,gingerwizard/elasticsearch,uschindler/elasticsearch,gfyoung/elasticsearch,gfyoung/elasticsearch,gingerwizard/elasticsearch,nknize/elasticsearch,robin13/elasticsearch,scorpionvicky/elasticsearch,gingerwizard/elasticsearch