Toggle gossip off when head block time is 30 seconds away

[sgerbino]

Brief description

When you haven't applied a head block within the last 30 seconds, toggle gossip off.

Checklist

• [x] I have built this pull request locally
• [x] I have ran the unit tests locally
• [ ] I have manually tested this pull request
• [x] I have reviewed my pull request
• [ ] I have added any relevant tests