Range deletion thread uses a single opCtx for the entirety of its lifetime, which is similar to the balancer main thread. Single opCtx are convenient and avoids repeated context/session creation overhead. However, it risks building up lots of resource(including memory) over time. 

Investigate the memory implications of the long lived opCtx and consider replacing this pattern with shorter lived contexts—potentially one per deletion task or balancer round—to improve memory efficiency and provide clearer operation metrics.

This pattern also creates misleading operation metrics where cumulative wiredTiger session statistics get attributed to individual operations as seen in HELP-83942.