Proto/tests: refactor wait functions

Depends on !12208 (merged)

What

Refactor wait_cycles functions

Why

More use cases

How

1. Extract the cycle bake from next_cycle
2. Put it in wait_cycle
3. ???
4. Profit!

Manually testing the MR

Tests should give the same results as before

dune exec src/proto_alpha/lib_protocol/test/integration/main.exe -- --match "test_scenario.*\.ml"

Checklist

• Document the interface of any function added or modified (see the coding guidelines)
• Document any change to the user interface, including configuration parameters (see node configuration)
• Provide automatic testing (see the testing guide).
• For new features and bug fixes, add an item in the appropriate changelog (docs/protocols/alpha.rst for the protocol and the environment, CHANGES.rst at the root of the repository for everything else).
• Select suitable reviewers using the Reviewers field below.
• Select as Assignee the next person who should take action on that MR