Bump co.elastic.clients:elasticsearch-java

Bumps [co.elastic.clients:elasticsearch-java](https://github.com/elastic/elasticsearch-java) from 7.17.0 to 8.15.0.
- [Release notes](https://github.com/elastic/elasticsearch-java/releases)
- [Changelog](https://github.com/elastic/elasticsearch-java/blob/main/CHANGELOG.md)
- [Commits](elastic/elasticsearch-java@v7.17.0...v8.15.0)

---
updated-dependencies:
- dependency-name: co.elastic.clients:elasticsearch-java
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <support@github.com>

data-prepper-plugins/opensearch/build.gradle

@@ -35,7 +35,7 @@ dependencies {
     implementation libs.caffeine
     implementation 'software.amazon.awssdk:apache-client'
     implementation 'software.amazon.awssdk:netty-nio-client'
-    implementation 'co.elastic.clients:elasticsearch-java:7.17.0'
+    implementation 'co.elastic.clients:elasticsearch-java:8.15.0'
     implementation('org.apache.maven:maven-artifact:3.9.8') {
         exclude group: 'org.codehaus.plexus'
     }