RAFT: fix race between apply for classes in the schema and report ready only after db reloaded

[moogacs]

What's being changed:

this PR add a fix to handle data races on accessing the schema classes st.db.Schema.Classes
those situation can happen if there is concurrent apply at the same time and in this change we reload the db from introduced new func reloadDBFromSchema() which serialize access to schema classes

also convert dbLoaded flag to be set in reloadDBFromSchema() func only given that flag is used to report ready and in case of recovering we need to reload the db before reporting ready to have the consistent state for query

Review checklist

• Documentation has been updated, if necessary. Link to changed documentation:
• Chaos pipeline run or not necessary. Link to pipeline:
• All new code is covered by tests where it is reasonable.
• Performance tests have been run or not necessary.

[sonarcloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
No data about Coverage
0.0% Duplication on New Code

See analysis details on SonarCloud