When read or write operations are performed on a DC with RF=0 with LOCAL_QUORUM
or LOCAL_ONE consistency level, Cassandra throws `Unavailable` exception.
Scylla allowed such read operations and failed write operations with a cryptic:
"broken promise" error. This occured because the initial availability
check passed (quorum of 0 requires 0 replicas), but execution failed
later when no replicas existed to process the mutation.
This patch adds an explicit RF=0 validation for LOCAL_ONE and LOCAL_QUORUM that
throws before attempting operation execution.
The change also requires `test_query_dc_with_rf_0_does_not_crash_db` to be
upgraded. This testcase was asserting somewhat similar scenario, but wasn't
taking into account the whole matrix of combinations:
- scenarios: successful vs unsuccesful operation outcome
- local consistency levels: LOCAL_QUORUM & LOCAL_ONE
- operations: SELECT (read) & INSERT (write)
and so it's been extended to cover both the pre-existing and the current issues
and the whole matrix of combinations.
Fixes: scylladb/scylladb#27893
d4c28690e1