malus-collator: implement malicious collator submitting same collation to all...

malus-collator: implement malicious collator submitting same collation to all backing groups (#6924)

## Issues
- [[#5049] Elastic scaling: zombienet
tests](https://github.com/paritytech/polkadot-sdk/issues/5049)
- [[#4526] Add zombienet tests for malicious
collators](https://github.com/paritytech/polkadot-sdk/issues/4526)

## Description
Modified the undying collator to include a malus mode, in which it
submits the same collation to all assigned backing groups.

## TODO
* [X] Implement malicious collator that submits the same collation to
all backing groups;
* [X] Avoid the core index check in the collation generation subsystem:
https://github.com/paritytech/polkadot-sdk/blob/master/polkadot/node/collation-generation/src/lib.rs#L552-L553;
* [X] Resolve the mismatch between the descriptor and the commitments
core index: https://github.com/paritytech/polkadot-sdk/pull/7104
* [X] Implement `duplicate_collations` test with zombienet-sdk;
* [X] Add PRdoc.