handle corrupt create metakv tokens

In a customer case, we have seen that there exists a corrupt CreateCommand token in metakv (symptoms similar to what we have seen in MB-46369 and MB-46085)

Because of such corrupt tokens, rebalance fails on `RetrieveLivePlanFromCluster`. Also creation of index will be driven by round robin strategy instead of SAPlanner/GreedyPlanner.

We should handle such corrupt tokens more gracefully and not let rebalance fail at the least.

Although we have fixed a possibility of generating such corrupt tokens in 7.0, if we already have such corrupt tokens then system cannot get out of it unless the customer manually deletes it. Hence adding v7+ in affects version