Avoid the failed meta replica region temporarily in Load Balance mode

This is a follow-up enhancement with Stack, Duo. With the newly introduced meta replica LoadBalance mode, if there is something wrong with one of meta replica regions, the current logic is that it keeps trying until the meta replica region is onlined again or it reports error, i.e, there is no HA at LoadBalance mode. HA can be implemented if it reports timeout with one meta replica region and tries another meta replica region.