torture: Set configfile variable to current scenario

The torture-test recheck logic fails to set the configfile variable to
the current scenario, so this commit properly initializes this variable.
This change isn't critical given that all errors for a given scenario
follow that scenario's heading, but it is easier on the eyes to repeat it.
And this repetition also prevents confusion as to whether a given message
goes with the previous heading or the next one.

Signed-off-by: Paul E. McKenney <paulmck@kernel.org>