fix: rollout calculation to prevent drop all ready rooms

[reinaldooli]

This PR apply some changes in how maestro manages rollouts:

• It calculates the amount of rooms to surge based on the current total target of rooms, preventing health controller miscalculations;
• Cap the amount of rooms to surge, taking in consideration pending rooms, preventing creation loop;
• Take in count the ready target to drop rooms during rollouts;
• Rollout operations don't block health controller operations, allowing the health controller to handle changes faster;