[3.1.1 backport] Retry to insert config when write fails

CBG-2282 increased the timeout of bootstrap connections to 10 seconds. This is good for helping avoid a failed write however if this times out, then nothing is done to retry the write and the database fails to be added.

Retry handling needs to be added around inserting a config in to the database so that if the write fails, it has a chance to still succeed (even if it causes an increase in the REST API response). The write must be CAS safe to make sure nothing is overwritten.