fix(data-point-service): resetCache should clear stale data

[schiavig]

resetCache should clear stale data

fix #492

What: resetCache doesn't remove stale data so, it happens that for removed contents it still provide old data

Why:

How: removing stale data on promise chain

Checklist:

• [ ] Has Breaking changes N/A
• [x] Documentation
• [x] Tests
• [x] Ready to be merged
• [x] Added username to all-contributors list