PR description

use reputation score to sort peers within EthPeers (bestPeerComparator)

Note in a few places in tests I've explicitly set the comparator to what was used before (uses chain height estimate) to avoid having to update a heap of tests that are dependent on the decision made by the comparator
ref #6968

Thanks for sending a pull request! Have you done the following?

• Checked out our contribution guidelines?
• Considered documentation and added the doc-change-required label to this PR if updates are required.
• Considered the changelog and included an update if required.
• For database changes (e.g. KeyValueSegmentIdentifier) considered compatibility and performed forwards and backwards compatibility tests

Locally, you can run these tests to catch failures early:

• unit tests: ./gradlew build
• acceptance tests: ./gradlew acceptanceTest
• integration tests: ./gradlew integrationTest
• reference tests: ./gradlew ethereum:referenceTests:referenceTests