Display multitest setup and teardown times on webUI

[rnemes]

Bug / Requirement Description

Users would like to see multitest setup and teardown duration on the Nav bar.

Checklist:

• [x] Test
• [ ] Example (both test_plan.py and .rst)
• [ ] Documentation (API)
• [x] News fragment present for release notes
• [x] MS info leakage check
• [ ] For new driver: driver index page
• [ ] For new assertion: ui/pdf/std renderers, documentation
• [ ] For new cmdline arg: documentation