Improve CI pipeline of indexer
- push to a 
nextbranch instead ofmaster, indexnextbranch into Solr, then switch tomaster - what if indexation is interrupted? could we index in a sort of 
nextbranch of Solr, then merge to normal index? 
next branch instead of master, index next branch into Solr, then switch to master
next branch of Solr, then merge to normal index?