`database::find_column_family()` throws no_such_column_family
if an unknown ks.cf is fed to it. and we call into this function
without checking for the existence of ks.cf first. since
"/storage_service/tablets/move" is a public interface, we should
translate this error to a better http error.
in this change, we check for the existence of the given ks.cf, and
throw an exception so that it can be caught by seastar::httpd::routers,
and converted to an HTTP error.
Fixes#17198
Signed-off-by: Kefu Chai <kefu.chai@scylladb.com>
Closesscylladb/scylladb#17217