[SPARK-57078] Upgrade Dropwizard metrics to 4.2.39

### What changes were proposed in this pull request?

This PR aims to upgrade `Dropwizard` metrics to 4.2.39.

### Why are the changes needed?

To bring the latest bug fixes including the official Java 25 support.

- https://github.com/dropwizard/metrics/milestone/109?closed=1
  - dropwizard/metrics#4964

### Does this PR introduce _any_ user-facing change?

No.

### How was this patch tested?

Pass the CIs.

### Was this patch authored or co-authored using generative AI tooling?

Generated-by: Claude Opus 4.7

Closes #690 from dongjoon-hyun/SPARK-57078.

Authored-by: Dongjoon Hyun <dongjoon@apache.org>
Signed-off-by: Dongjoon Hyun <dongjoon@apache.org>

Author: dongjoon-hyun

gradle/libs.versions.toml

@@ -19,7 +19,7 @@ fabric8 = "7.7.0"
 lombok = "1.18.46"
 netty = "4.2.14.Final"
 operator-sdk = "5.3.4"
-dropwizard-metrics = "4.2.38"
+dropwizard-metrics = "4.2.39"
 spark = "4.2.0-preview5"
 hadoop = "3.5.0"
 log4j = "2.26.0"