Cut over to new metaData#concreteIndices(IndicesOptions, String...) for all the api previously using MetaData#concreteIndices(String[], IndicesOptions)

Removed old unused method, deprecation is not needed as it doesn't break client code.
Introduced constants for flags in IndicesOptions for more readability
Renamed MetaData#concreteIndex to concreteSingleIndex

Left it as a shortcut although it calls the common concreteIndices that accepts IndicesOptions and multipleIndices