Some complex queries fail for advanced global search

https://sentry.gitlab.net/gitlab/gitlabcom/issues/1468715/?query=is%3Aunresolved

Complex ES query ("slack integration" for example) for issues scope fails with

"caused_by": { - 
            "type": "illegal_state_exception",
            "reason": "field:[title] was indexed without position data; cannot run PhraseQuery"
          }

#28085 (closed)