Increase round duration to approximately 2 hours - external proposal 0x503be4

Summary of Proposed Change

• Active Collators Determined Every 2 Hours: The change will set the determination of active collators to occur every 2 hours, instead of every 4 minutes.
• Reward Calculation and Payouts: Rewards will be calculated and paid out every 2 hours, reducing the frequency from every 4 minutes.
• Resource Allocation: This change will free up resources currently used for these intense operations, allowing more resources for transactions.
• Bond Decrease and Candidate Set Changes: Decreasing bonds or leaving the candidate set will now take 4 hours instead of the previous shorter period.
• Blocks per Round Increase: Increasing the blocks per round is necessary to expand the active collator set size.
• Moonriver Example: The decision to use 2 hours is based on the example of Moonriver, a Kusama parachain that uses a similar system.