[ES|QL] change `isDevVersion` to `this.isDevVersion` in ANTLR grammars

[drewdaemon]

Description

All code in the grammar files must be compatible with both Java and Javascript in order for Kibana to consume these files.

Javascript does not support an implicit this when invoking methods. It must be explicit (e.g. this.isDevVersion()).

[elasticsearchmachine]

Pinging @elastic/es-analytical-engine (Team:Analytics)

[elasticsearchmachine]

Pinging @elastic/kibana-esql (ES|QL-ui)