Currently CREATE KEYSPACE ... WITH STORAGE = { 'type' = 'S3' ... } will create keyspace even if the backend configuration is "invalid" in the sense that the requested endpoint is not known to scylla via object_storage.yaml config file. The first time after that when this misconfiguration will reveal itself is when flushing a memtable (see #15635), but it's good to know the endpoint is not configured earlier than that.
fixes: #15074Closesscylladb/scylladb#16038
* github.com:scylladb/scylladb:
test: Add validation of misconfigured storage creation
sstables: Throw early if endpoint for keyspace is not configured
replica: Move storage options validation to sstables manager
test/cql-pytest/test_keyspaces: Move DESCRIBE case to object store
sstables: Add has_endpoint_client() helper to manager