Configure the kafka clusters environment for the consumer lag exporter

All the metrics are now gathered by the journal orchestrator. If the environment label is not forced per cluster, the environment of the orchestrator is used.

Test Plan

• getty:

diff origin/production/getty.internal.softwareheritage.org current/getty.internal.softwareheritage.org
*******************************************
  Profile::Prometheus::Export_scrape_config[kafka-consumer-group-rocquencourt] =>
   parameters =>
     labels =>
       environment =>
        + production
*******************************************
  Profile::Prometheus::Export_scrape_config[kafka-consumer-group-rocquencourt_staging] =>
   parameters =>
     labels =>
       environment =>
        + staging
*******************************************
*** End octocatalog-diff on getty.internal.softwareheritage.org

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Migrated from D7020 (view on Phabricator)