Ensure Heartbeat is configured to write to older versions of ES

[paulb-elastic]

With the change that’s being implemented to prevent beats from writing to older versions of ES, we need Heartbeat running in the Synthetic Service to override this, so that it can write to older versions.

Heartbeat has typically been very backward compatible, and we are expecting to only have one version (latest) of Heartbeat running in the (multi tenant) Synthetic Service, which will be writing results back to numerous different versions.

ACs:

• Heartbeat running in the service will be configured with the output.elasticsearch.allow_older_versions=true property to ensure it can write results back to older versions of ES (see Only connect to Elasticsearch instances with the same version or newer beats#29683 for more details)

[paulb-elastic]

Closing - wrong repo...