This patch adds a reproducer for issue #11954: Attempting an
"IF NOT EXISTS" (LWT) write with a null key crashes Scylla,
instead of producing a simple error message (like happens
without the "IF NOT EXISTS" after #7852 was fixed).
The test passed on Cassandra, but crashes Scylla. Because of this
crash, we can't just mark the test "xfail" and it's temporarily
marked "skip" instead.
Refs #11954.
Signed-off-by: Nadav Har'El <nyh@scylladb.com>
Closes#11982
e393639114