Automatic merge from submit-queue

Use mCPU as CPU usage unit, add version in PerfData, and fix memory usage bug.

Partially addressed #24436.

This PR:
1) Change the CPU usage unit to "mCPU"
2) Add version in PerfData, and perfdash will only support the newest version now.
3) Fix stupid mistake when calculating the memory usage average.

/cc @vishh