Migration path from badger to pebble

[raultorrecilla]

Problem statement

As we are probably going to replace badger for pebble (in this issue) we now have to think and test a migration path for 9.0 version.
The replacement of this library will lead to customers loosing data that were considered for TBS but didn't yet have a sampling decision.

### Proposed solution
Create migration plan and test it for applicable versions