Fix `solochain-template-runtime` freezes config (#5846)

# Description

Sets the correct `RuntimeFreezeReason` type for
`solochain-template-runtime` configuration of pallet_balances.

## Review Notes

For whatever reason `RuntimeFreezeReason` is currently set to
`RuntimeHoldReason`. This in turn causes problems with variant counting
in `MaxFreezes` and results in pallet_balances integrity tests failing
whenever hold/freeze reasons are added to the runtime.
This fixes it by simply setting `RuntimeFreezeReason` to
`RuntimeFreezeReason` in pallet_balances Config.