Enable the swh-search environment in staging

Actions:

• Deploy a dedicated elasticsearch node (1 node to start, we'll see if a cluster is needed)

• Deploy a rpc search service

• webapp.staging uses the search service

• Deploy a search journal client (read from kafka / Write to ES)

• Deploy a search journal client for indexed metadata topic [1]

• [1] Deployed but currently stuck due to #2876 (closed)

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Migrated from T2817 (view on Phabricator)