Bring back the on_finalize weight of staking. (#8463)

* Bring back the on_finalize weighg of stakin.

* Better logs

* Also make a few things pub

* Fix build

* Add assertions

* Add test.

* remove dbg

* Update frame/election-provider-multi-phase/src/unsigned.rs

* Update frame/staking/src/tests.rs

* Fix

* Fix

* Update frame/election-provider-multi-phase/src/unsigned.rs