Unable to turn off telemetry

The telemetry opt-out options described at https://hasura.io/docs/1.0/graphql/manual/guides/telemetry.html#how-do-i-turn-off-telemetry-opt-out seem to have no effect.

I'm using Docker and specified `HASURA_GRAPHQL_ENABLE_TELEMETRY: "false"` in the `environment` section of the `graphql-engine` service. Also set `enable_telemetry: false` in `config.yaml`. Even then, I see Hasura console making a WebSocket connection to `wss://telemetry.hasura.io/v1/ws` and messages being transmitted on console actions.

I'm using the `hasura/graphql-engine:v1.2.0-beta.3` image (although the same happened in v1.1.1).