It's a part of an initiative of bringing wtperf YCSB closer to MongoDB YCSB (WT-17498). 

MongoDB measures YCSB in different configurations, and some of them are part of its high-value workload suite. Currently, with the existing variants, we have 95read5update and 100read, which already match similar out-of-cache MongoDB configurations.

The scope of this ticket is to add two new in-cache configurations and rename the files to highlight the importance of these benchmarks.