is_supported_by checks whether a given restriction
can be supported by some index.
Currently when a subscripted value, e.g `m[1]` is encountered,
we ignore the fact that there is a subscript and ask
whether an index can support the `m` itself.
This looks like unintentional behaviour leftover
from the times when column_value had a sub field,
which could be easily forgotten about.
Scylla doesn't support indexes on collection elements at all,
so simply returning false there seems like a good idea.
Signed-off-by: Jan Ciolek <jan.ciolek@scylladb.com>
Closes#10227