Provide an endpoint to create aliases for all existing indices that do not have aliases

This is follow-up of fix for issue Multi kind search does not work with more than approximately 85 kinds.

In this MR, we add an endpoint that allows cloud operators to create aliases for all existing indices. Doing that, queries from a given data partition won't trigger the alias creation operation in the search service after the endpoint is called once for the given data partition.

Please note that previous change in search service still works even the cloud operators don't call this new endpoint if they don't have time now. However, it is still recommended to explicitly call it once for all existing data partitions.