Fix fast-unstake for accounts with slashing (#12963)

* Fix fast-unstake for accounts with slashing

* ".git/.scripts/fmt.sh" 1

* fmt

* fix

* fix weight tracking

* Adds tests for withdraw_unbonded with slashing

* Removes tests for withdraw_unbonded with slashing

* ".git/.scripts/fmt.sh"

* Adds slash spans calculation test for withdraw_unbonded

Co-authored-by: command-bot <>
Co-authored-by: gpestana <[email protected]>