seaweedfs: pool names "lock" and "readonly" collide with the instance COSI classes #5316

The SeaweedFS app refuses pool names ending in -lock or -readonly, but it accepts the bare names lock and readonly, and those collide with the instance's own COSI classes.

• A pool named lock renders a BucketClass <namespace>-lock from templates/storage-pool-bucket-classes.yaml. The instance already has a BucketClass with that name in templates/client/cosi-bucket-class.yaml: the object-lock class.
• A pool named readonly renders a BucketAccessClass <namespace>-readonly, which is the same name as the instance's read-only access class.

Either way the release renders two objects of the same kind and name, so the pool's class and the instance's class cannot both exist.

The check in packages/extra/seaweedfs/templates/seaweedfs.yaml should also reject the exact names lock and readonly, for volume.pools and per-zone pools alike. #5252 adds the same check for public, so the fix can reuse its shape.