Feat: Improved approach of checking users for liqudation by bucketing…

[ssamarakoon]

Improved liquidator by checking on users with lower health more via a bucketed-by-health approach.

Prioritizes unhealthy users by using weighted randomization to select which bucket to check:

• 80% of time check very unhealthy users (<5% health),
• 8% of time check almost unhealthy users (5-20% health),
• 2% of time check healthy users (>20% health),
• 10% of time check liquidatable users