torture: Remove RCU_FAST_NO_HZ from rcu scenarios

All of the rcu scenarios that mentioning CONFIG_RCU_FAST_NO_HZ disable it.
But this Kconfig option is disabled by default, so this commit removes
the pointless "CONFIG_RCU_FAST_NO_HZ=n" lines from these scenarios.

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