Fix timestamp logic in UnseenTopFeed Manager minds#3200

Ticket(s) / Related Merge Requests

Fixes an issue with minds#3200 (closed)

Summary of Changes

The feeds elastic manager didn't support giving a single from_timestamp as a lowerbound to an algorithm that was descending by default. So as a solution, we can use two reversed bounds.

Testing Considerations

Same as minds#3200 (closed)

Deployment Considerations

N/A

Regression Scope

N/A

Platform Affected (web, mobile, etc)

All

Developer Testing Completed

local

Screenshots / Screen Recording

Does this impact

• Localization
• Dark/light mode
• Guest mode

Definition of Done Checklist

• The Acceptance Criteria has been met
• Code is tested: Testing includes unit/spec, E2E/automated and manual testing
• Merge requests description has been filled out