cql: set configurable restriction of DateTieredCompactionStrategy to warn by default
cql: set configurable restriction of DateTieredCompactionStrategy to warn by default

Setting a value of "warn" will still allow the create or alter commands,
but will warn the user, with a message that will appear both at the log
and also at cqlsh for example.

This is another step towards deprecating DTCS. Users need to know we're
moving towards this direction, and setting the default value to warn
is needed for this. Next step is to set it to false, and finally remove
it from the code base.

Refs #8914.

Signed-off-by: Raphael S. Carvalho <1e2942cea40e3b4d2162dfcd9e53e41c05a84d22@scylladb.com>
Message-Id: <20211029184503.102936-1-1e2942cea40e3b4d2162dfcd9e53e41c05a84d22@scylladb.com>

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