scx_utils: Display the tag value for nested counters in log_recorder

The log_recorder was incorrectly displaying the tag name instead of the
value for nested counters.

Signed-off-by: Jose Fernandez <josef@netflix.com>

rust/scx_utils/src/log_recorder.rs

@@ -172,7 +172,7 @@ pub trait MetricFormatter {
             Some(percentage) => {
                 // Assuming only one label for now
                 let name = match key.labels().next() {
-                    Some(label) => label.key(),
+                    Some(label) => label.value(),
                     None => "Unknown",
                 };