Add cronjob for purging soft deleted data from db

[Pitasi]

With Tracelistener 1.4.0 we started soft deleting data instead of deleting the row entirely. This affects the following tables: delegations, unbonding_delegations, validators.

I don't personally think it's going to be a huge problem in the near future but we need to acknowledge that this data can grow over time and we can purge for good rows that have been deleted some time ago.

We can do that as a k8s cronjob, as a custom microservice, or even inside tracelistener if we want.

DoD:

• periodically delete rows that have an "old" delete_height column (e.g. delete_height is older than current chain height - 100?) from all the tracelistener tables