Calcul node reward based on scheduler time

[Neylix]

Describe the problem you discovered

Actually the node_reward transaction is sent based on a configurable interval. n production this interval is set to 1 transaction per day.
In the reward calculation we get the number of days of the current month and divide 50 by this number. This fit well for production configuration but if the node_reward transaction are sent in a different interval than once a day, the reward calculation is not accurate.

Describe the solution you'd like

We should divide the monthly reward amount (currently 50$) by the number of interval in the current month