approval-voting: Make sure we always mark approved candidates approved in a...

approval-voting: Make sure we always mark approved candidates approved in a different relay chain context (#4153)

... see for more detail why this is needed

https://github.com/paritytech/polkadot-sdk/issues/4149#issuecomment-2058472444

## TODO:
- [x] Unittests
- [x] Replicate scenario from
https://github.com/paritytech/polkadot-sdk/issues/4149 and confirm this
fixes it: https://github.com/paritytech/polkadot-sdk/issues/4149

 [
Replicated on a zombienet with some hacked nodes, that we can end up in
this state where no-wake is schedule and the nodes are pending new
assignments]

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Signed-off-by: Alexandru Gheorghe <[email protected]>
Co-authored-by: Andrei Sandu <[email protected]>