Fix db_cleaner.js to keep updating from_time

[jackyalbo]

Explain the changes

1. As part of fixes to md_aggregator and system_store we stopped loading the system_store on every md_aggregator cycle, instead, we added an option to support global_last_update in the system.
2. As part of this change we missed updating db_cleaner as well with this new structure. Now it was added and from time can advance and allow db_cleaner to run.

Issues: Fixed #xxx / Gap #xxx

1. Fixed https://bugzilla.redhat.com/show_bug.cgi?id=2305978

Testing Instructions:

1. Go over the steps in the BZ above and make sure you eventually stop seeing/not seeing any
   waiting for md_aggregator to advance to later than, and you see md_aggregator at keep updating
   like this:

Aug-21 13:38:18.302 [BGWorkers/36]    [L2] core.server.bg_services.db_cleaner:: DB_CLEANER: md_aggregator at 2024-08-21T13:36:17.104Z
Aug-21 13:38:18.303 [BGWorkers/36]    [L0] core.server.bg_services.db_cleaner:: DB_CLEANER: found less than 1000 objects in MD-STORE
Aug-21 13:38:18.305 [BGWorkers/36]    [L0] core.server.bg_services.db_cleaner:: DB_CLEANER: found less than 1000 nodes in nodes-store
Aug-21 13:38:18.306 [BGWorkers/36]    [L0] core.server.bg_services.db_cleaner:: DB_CLEANER: found less than 1000 docs in system-store
Aug-21 13:38:18.306 [BGWorkers/36]    [L0] core.server.bg_services.db_cleaner:: DB_CLEANER: END
Aug-21 13:39:18.310 [BGWorkers/36]    [L0] core.server.bg_services.db_cleaner:: DB_CLEANER: START
Aug-21 13:39:18.310 [BGWorkers/36]    [L2] core.server.bg_services.db_cleaner:: DB_CLEANER: md_aggregator at 2024-08-21T13:37:21.638Z
Aug-21 13:39:18.311 [BGWorkers/36]    [L0] core.server.bg_services.db_cleaner:: DB_CLEANER: found less than 1000 objects in MD-STORE
Aug-21 13:39:18.312 [BGWorkers/36]    [L0] core.server.bg_services.db_cleaner:: DB_CLEANER: found less than 1000 nodes in nodes-store
Aug-21 13:39:18.316 [BGWorkers/36]    [L0] core.server.bg_services.db_cleaner:: DB_CLEANER: found less than 1000 docs in system-store
Aug-21 13:39:18.316 [BGWorkers/36]    [L0] core.server.bg_services.db_cleaner:: DB_CLEANER: END

• Doc added/updated
• Tests added