After WT-18587 the tier.meta, tiered.meta, and object.meta methods and tiered_tree_config remain. They are the metadata schemas for refused tier: / tiered: / object: URIs. Nothing in C uses them as WT_CONFIG_BASE. Do not delete them until WT-18601 has covered an enabled leftover database.

Definition of done

- Those Method entries and tiered_tree_config are gone
- An enabled leftover open from WT-18601 does not need them