Fix Peak RPS calculation, shared tooltip and fix VU display in the Performance Overview

[Sea-you]

• Add a fix to the Peak RPS calculation by adding the Reduce (to max) transformation.
• Set shared tooltip in the Performance Overview panel
• Calculate the number of VUs by summing instead of average as it might mislead if you're testing with multiple instances. In our case 4 nodes, each 250 VUs. Previously this would have been displayed as 250 instead of 1000.

[CLAassistant]

All committers have signed the CLA.

[ppcano]

@Sea-you, thanks for fixing this and the improvements.

I think it is ready after removing the id property.

[olegbespalov]

Thanks for the contribution. I'll address linter issues separately 👍

[ppcano]

@Sea-you, thanks for fixing the issue, improving the dashboard, and sharing it with the community!