[Chore]: ensure Provider Boost changes use reducible_balance instead of balance for production calls

[shannonwells]

Feature Description

Details

Polkadot-sdk recommends using reducible_balance, and that balance calls are useful mainly for testing. Since PB deals with account balances, ensure that anywhere there is a balance call in production code uses reducible_balance instead. Note there is likely 0 or 1 of these.