Only calculate thread UUIDs if they are needed

MSP-11147

Only calculate thread UUIDs if the thread count exceeds
EXPECTED_THREAD_COUNT_AROUND_SUITE.
Include Thread status when printing leaked threads

MSP-11147

Sometime travis-ci is showing leaked threads even when
'Msf::Framework#threads cleaner' is being used, so I'm adding the
`Thread#status` to the data printed about the Thread to see if the
sometimes leaked threads have an odd status.  There's still a chance
that there will be a race-condition between when I call Thread.list and
I ask for each Thread's status that the VM could finish aborting a
Thread so that status I print isn't the same as the one that caused the
Thread to be returned in Thread.list.