test(consensus): fix flaky TestTooFarInTheFutureProposal

[lklimek]

Issue being fixed or feature implemented

TestTooFarInTheFutureProposal does not test if the proposal is too much in future.

What was done?

• refactored proposal processing in tests to allow setting proposal delivery using a middleware
• refactored proposal-based timestamp to get more precise error description when proposal is not timely, and assert for this error in tests

How Has This Been Tested?

Run GHA tests

Breaking Changes

None

Checklist:

• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have added or updated relevant unit/integration/functional/e2e tests
• I have made corresponding changes to the documentation

For repository code-owners and collaborators only

• I have assigned this pull request to a milestone