The work around for resolving `now` doesn't need to be used for aliases, becuase alias filters are parsed at search time. However it can't be removed, because the percolator relies on it.
Parent/child can be specified again in alias filters, this now works again because alias filters are parsed at search time. Parent/child will also use the late query parse work around, to make sure to do the final preparations when the search context is around. This allows the aliases api to validate the parent/child queries without failing because there is no search context.
Closes#10485
53874bf5a6