In "show throttles", also renames 'total' column to 'actual' to reflect that it is not necessarily the throttles requested for/by the client.
Also fills out 'target' in non-adapative mode to the actual throttle requested for/by the client.
This was because specifying a max client throttle would always request the max from the parent server throttle, no matter the actual total requests on the client throttle.
This would lead to a lower server multiplier than expected.
This change also adds a 'target' column to the "show throttles" output that shows the target rate (as set by client) if adaptive throttles is active.
This commit also re-adds the functionality lost in recent 5c1a1458 to set a max client throttle when adaptive is active.
This commit also adds TestClientThrottlePerClientAndRegionLimited and TestClientThrottleAdaptiveNoLimit regression tests
This only had one child, which is the 'adaptive' token bucket.
So from testing and currently analysis, we can use that bucket directly which simplifies the code.
