[Backport MB-39067 to 6.0.5] Index creation may fail in case of one or more watchers are not available

On GSI client, if WatchMetadata doesn't succeed for a subset of indexer nodes, the prepare create request and commit request will be sent only to the available watchers. But the planner considers all available indexer nodes for planning. If planner decides to put the index on the node for which watcher was not available, the index creation may fail.