Problem

*wt_config_tiered_strip was inlined to *wt_config_merge(..., "tiered_storage=(shared=),", ...) during leftover cleanup. shared is still a runtime override that must not be persisted, so the same strip remains at the metadata write sites. The named helper should have stayed.

Change

Restore __wt_config_tiered_strip and call it from file create and metadata turtle config.

Test

Existing schema/create coverage. No new tests.