Tighten Ringpop Join Params

[shawnhathaway]

What changed?

• Parallelism Factor: 2 -> 10 and Join Size: 3 -> 1
  • This ensures we can join a two node cluster.
  • This will also help in the case that IP addresses are changing on restart to allow us to go through a larger number of candidates
• Reduce heartbeat sleep interval and add jitter to prevent all nodes aligning (Heartbeat every 10-15 Seconds)
• Heartbeat cutoff time for reading candidate seed nodes reduced to 20 seconds.

How did you test it?
Ringpop unit tests

Potential risks
This shouldn't add additional risk.