Displays only invoked tests in fuel health output

Currently we're showing last tests in fuel health output, so if you run
sanity checks:

    $ fuel health --env X --check sanity

and then run platform_tests checks:

    $ fuel health --env X --check platform_tests

the fuel health shows both sanity and platform_tests testsets (since
sanity checks was ran recently). That's wrong behaviour, so since now
we're going to show only those tests which was ran by user.

Change-Id: I3ae09a99f2492713a0787a373aadc97ff646bddb
Closes-Bug: #1387157
Merge "Displays only invoked tests in fuel health output"