database: throw internal error when failing uuid returned by find_uuid
database: throw internal error when failing uuid returned by find_uuid

find_uuid returns a uuid found for ks_name.table_name.
In some cases, we immediately and synchronously use that
uuid to lookup other information like the table&
or the schema.  Failing to find that uuid indicates
an internal error when no preemption is possible.

Note that yielding could allow deletion of the table
to sneak in and invalidate the uuis.

Signed-off-by: Benny Halevy <23c997c90eb8537635e9392d48e7af1bf1b2ca22@scylladb.com>

scylladb/scylla,scylladb/scylla,scylladb/scylla,scylladb/scylla