Dont track inactive validators on rewards table

[santi1234567]

Description

The t_validator_rewards_summary table is an essential part of goteth as it provides very useful information on rewards from validators and their performance. At the moment, the table stores data from all validators from the network (active and inactive). The only reason for this to make sense is because the rewards table tracks also balance, which is a metric that might be of interes from inactive validators.

The overhead on the disk usage of the rewards table just to store balance does not make sense and this should be looked into. At the moment of writing this, 41% of the validators on the network are inactive, meaning that ~41% of the disk usage of the table is pretty much useless. With the upcoming changes from EIP-7251, the % of inactive validators should increase significantly as validators start consolidating (see #153).

The proposal is to remove inactive validators from the table and potentially also add an optional balances table to track balance history if this is desired.

[leobago]

Thanks for raising this issue Santi. Yes, tracking the balance of inactive validators is not the purpose of the rewards table, so we should remove them and save that unnecessary space.