torture: Make kvm-series.sh give build numbers and totals

torture: Make kvm-series.sh give build numbers and totals

The kvm-series.sh script can easily be convinced to do on the order
of 1,000 builds, so some sort of progress indicator would be helpful.
This commit therefore updates the "Starting" output lines to read
as in the following example, adding the ("2 of 4"):

Starting TREE01/1.7e0ad1b49057 (2 of 4) at Sat Nov 8 10:08:21 PM PST 2025

Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Boqun Feng <boqun.feng@gmail.com>