fix(network): Respond to getheaders requests with a maximum of 160 block headers

[arya2]

Motivation

This PR fixes a bug in Zebra's network protocol implementation where Zebra will return fewer than the expected maximum number of block headers in response to getheaders requests which has been falsely indicating to peers that they have reached the tip of Zebra's chain.

This doesn't strictly block the release if we want to also ignore getheaders requests during Zebra's initial sync.

Closes #8907.

Solution

• Returns a maximum of 160 block headers in response to getheaders requests instead of 158

PR Author's Checklist

• The PR name will make sense to users.
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• The solution is tested.
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PR Reviewer's Checklist

• The PR Author's checklist is complete.
• The PR resolves the issue.