erin.zhu@mongodb.com and I noticed some mis-accounting going on while investigating a performance BF which might have been partially attributable to us starting to store more query stats, even though we are using the same-ish amount of space (after/around SERVER-79736).

This ticket tracks the work to better account for space used, and to add some more testing around it. Specifically, I noticed: 

• query_stats::FindCmdComponents::size() fails to account for the sizeof(*this)
• query_shape::FindCmdShapeComponents::size() accidentally uses sizeof(this) (pointer) instead of sizeof(*this) (struct).