Eventually stop logging threads that died with an error
Eventually stop logging threads that died with an error

To avoid boundless growth of the thread heartbeat collection, once a
thread has been dead for HAB_THREAD_DEAD_IGNORE_DELAY_SECS, stop
logging it. Default delay: 1 week.

Signed-off-by: Jon Bauman <e6c6a4db54ad11b4de69fed67139594b59f3444f@users.noreply.github.com>

habitat-sh/habitat,rsertelon/habitat,habitat-sh/habitat,habitat-sh/habitat,habitat-sh/habitat,rsertelon/habitat,rsertelon/habitat,rsertelon/habitat,habitat-sh/habitat,rsertelon/habitat,rsertelon/habitat,rsertelon/habitat,habitat-sh/habitat,habitat-sh/habitat,habitat-sh/habitat