Remove WalReceiverSaturation indicator
What does this MR do and why?
Remove WalReceiverSaturation
indicator. As WalReceiverSaturation
is halting BBM most of the time, we decided to remove this saturation indicator, as BBMs are not causing a significant impact on the database performance.
WalReceiverSaturation
is already disabled for production and staging.
Related to #507523