As described in the parent task, Optimize needs to create an installation ID so we can add this information to the data to be sent to production telemetry.
Implementation suggestion: add an installation ID field to `MetadataDTO` which is initialised along with the schemaVersion in `ElasticsearchMetadataService.initMetadataVersionIfMissing(..)`. The installation ID is only to be generated if no installation ID exists in the database. Note that we're currently happy if a cluster of Optimize instances overwrites each others installation ID due to race conditions, we will just use the last installation Id that has been written to the DB.
- Optimize creates and stores its installation ID