Clean up general purpose utility functions

[amesgen]

We have accumulated a non-trivial set of utility and helper functions in Ouroboros.Consensus.Util and Test.Util.Split.

• Several, especially list-based functions are only used in tests. They should probably not be implemented in Ouroboros.Consensus.Util in order to not make lists overly appealing as a data structure in our actual code. This is part of clearly distinguishing between the Ouroboros.Consensus.Util.* and Test.Util.* modules.
• We should remove unused functions (e.g. via weeder), and ensure that the ones we actually use are (property) tested or replaced by using a published library if appropriate.

Motivation for this ticket: https://github.com/input-output-hk/ouroboros-network/pull/3860#discussion_r1011909460

[jasagredo]

Related input-output-hk/ouroboros-network#4259