Use traverseP expression to build the sort key for the common key prefix case. We should make sure the expression for the common prefix is only calculated once. We might need to add a workload for a longer key prefix to make sure it doesn't regress.

Preliminary perf: https://performance-analyzer.server-tig.prod.corp.mongodb.com/perf-analyzer-viz/?evergreen_version=63c582a232f4171734d0e297&evergreen_base_version=performance_550e070c93e80bdb4f256dd634128ad919395eb0&metrics_selection=Latency99thPercentile||ops_per_sec||Latency50thPercentile||OperationThroughput||tpmC||NewOrders||Duration||average_read_latency_us||95th_read_latency_us||99th_read_latency_us&percent_filter=0||100&z_filter=0||10