scheduler-backend: Fix configuration key change

Related T1525

data/hostname/saatchi.internal.softwareheritage.org.yaml

@@ -7,4 +7,4 @@ swh::deploy::scheduler::remote::config:
   scheduler:
     cls: local
     args:
-      scheduling_db: "%{hiera('swh::deploy::scheduler::database')}"
+      db: "%{hiera('swh::deploy::scheduler::database')}"

[Phabricator Migration user]

Some references in the commit message have been migrated:

• T1525 is now #1525 (closed)