torture: Put kvm.sh batch-creation awk script into a temp file

This commit is a first step towards pinning guest-OS vCPUs so as
to force latency differences, especially on multi-socket systems.
The kvm.sh script puts its batch-creation awk script into a temporary
file so that later commits can add the awk code needed to dole out CPUs
so as to maximize latency differences.  This awk code will be used by
multiple scripts.

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