[BUG] Fix Grok recursion issue.

[CEHENKLE]

In Elasticsearch versions before 7.13.3 and 6.8.17 an uncontrolled recursion vulnerability that could lead to a denial of service attack was identified in the Elasticsearch Grok parser. A user with the ability to submit arbitrary queries to Elasticsearch could create a malicious Grok query that will crash the Elasticsearch node.https://cve.mitre.org/cgi-bin/cvename.cgi?name=2021-22144