Implement rollback on keyspace creation failure

## Enhancement Task
If the keyspace creation fails and cannot be successfully enabled, the operations performed during the creation process should be rolled back, and the keyspace status should be set to `tombstone`.

Start by tracing the keyspace creation flow and the step that enables the keyspace, since the issue names no files or tests. Identify each operation that must be reverted on failure; done means an unsuccessful creation rolls back those operations and leaves the keyspace in `tombstone` status.

Written by the indexing model from the issue text.