Correctly clean up gossip tracking goroutine when gossip is disabled

[mvandeberg]

Brief description

The go routine that logs gossip summaries does not exit when gossip is toggled off, but a new one is created every time Gossip is toggled back on. This PR cancels the go routine when gossip is toggled off so that only one copy of the routine is running at a time.

Checklist

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

Demonstration