s3:mdssvc: the open command must work on shares with Spotlight disabled

s3:mdssvc: the open command must work on shares with Spotlight disabled

Move the implementation of this setting down to the actual search query
processing. macOS has no notion of "spotlight = false" at the DCERPC layer and
the open request will always succeed even on all shares.

When later the client issues search requests on such shares, we ensure we use
the noindex backend.

Signed-off-by: Ralph Boehme <slow@samba.org>
Reviewed-by: Jeremy Allison <jra@samba.org>