Extract eviction thread management fields from __wt_connection_impl (lines 838-845) into a new WT_CONN_EVICT_THREADS structure. This includes evict_server_running, evict_threads (the WT_THREAD_GROUP), evict_threads_max, evict_threads_min, evict_sample_inmem, evict_use_npos, and evict_legacy_page_visit_strategy. Note: The main evict pointer (line 773) and cache pointer stay in the connection as they point to larger subsystems. Access will be via conn->evict_threads.<field>.

Files affected

• src/include/connection.h — Define WT_CONN_EVICT_THREADS structure and replace individual eviction thread fields
• src/evict/evict_conn.c — Update eviction thread startup/shutdown
• src/evict/evict_lru.c — Update eviction thread management
• Any files that configure or query eviction thread settings

Definition of Done

• New WT_CONN_EVICT_THREADS structure defined in connection.h containing eviction thread config
• All eviction thread fields removed from __wt_connection_impl and replaced with single evict_threads member
• All references updated from conn->evict_server_running to conn->evict_threads.server_running, etc.
• Code compiles cleanly with no warnings
• All existing tests pass
• Grep confirms no stale references to old eviction thread field paths