Upgrade all RC and AH accounts to new balance logic

[muharem]

The new balance introduced with paritytech/substrate#12951 has a different reference accounting strategy. The same PR introduced a lazy migration for all existing accounts to that strategy. The special flag within the account data indicates either that account migrated to the new logic or not.

In order to ignore that flag, reduce the work that needs to be done within AH migration and drop the events generated by that logic switch we migrate all existing accounts on Relay Chains and AHs before with dedicated for that balances::upgrade_accounts call.

[bkchr]

Please do not forget that downstream teams are using the same pallet. This means that the manual migration should be removed and rewritten as a multi block migration that can be executed by everybody.