Delarative partitioning

[greenape]

I have:

• [x] Formatted any Python files with black
• [x] Brought the branch up to date with master
• [x] Added any relevant Github labels
• [x] Added tests for any new additions
• [x] Added or updated any relevant documentation
• [ ] Added an Architectural Decision Record (ADR), if appropriate
• [ ] Added an MPLv2 License Header if appropriate
• [x] Updated the Changelog

Description

Changes the flowdb partitioning strategy from inheritance based, to declarative.

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 92.30%. Comparing base (4b89707) to head (693c4ab).

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #6679 +/- ## ======================================= Coverage 92.30% 92.30% ======================================= Files 268 268 Lines 10590 10590 Branches 856 856 ======================================= Hits 9775 9775 Misses 676 676 Partials 139 139 ```

:umbrella: View full report in Codecov by Sentry.
:loudspeaker: Have feedback on the report? Share it here.