Retry disable and enable of balancer in awaitCollectionBalance

As part of the shell helper function awaitCollectionBalance, the balancer is turned off to wait for orphan cleanup and then the balancer is reenabled. Turning on and off the balancer is done via writes to config.collections, which are not retriable since they are in the config collection.

We should retry these commands (1, 2) in case of notPrimary errors so that this helper can still be used in config stepdown suites.