elastic: Decrease concurrency to 5 max

Related to T4144

sysadmin/T3592-elastic-workers/worker/values.yaml

@@ -20,5 +20,5 @@ swh:
     version: 2022-04-28
     replicas:
       min: 1
-      max: 10
+      max: 5
 

[Phabricator Migration user]

Some references in the commit message have been migrated:

• T4144 is now swh/infra/sysadm-environment#4144 (closed)