[Marketplace] - Implement BlockHeader for TestBlockHeader properly

[ss-es]

What is this task and why do we need to work on it?

In #3569, get_auction_results was given a dummy implementation to allow running an integration test for a consensus upgrade to the marketplace version. Once the simple builder is updated to properly serve marketplace bundles, we should make sure BlockHeader (and other traits in example-types) have correct implementations for the test types.

What work will need to be done to complete this task?

No response

Are there any other details to include?

No response

What are the acceptance criteria to close this issue?

Test types get correct implementations with all tests passing.

Branch work will be merged to (if not the default branch)

No response