performance-metrics: Set default number of iterations to 5

Many of the tests already amortize their results over a longer time
period/sample so it is not necessary to run 30 iterations.

Signed-off-by: Rob Bradford <robert.bradford@intel.com>

performance-metrics/src/main.rs

@@ -119,7 +119,7 @@ impl PerformanceTestControl {
     const fn default() -> Self {
         Self {
             test_time: 10,
-            test_iterations: 30,
+            test_iterations: 5,
             queue_num: None,
             queue_size: None,
             net_rx: None,