Bump org.opensearch:opensearch-core

Bumps [org.opensearch:opensearch-core](https://github.com/opensearch-project/OpenSearch) from current to 2.18.0.
- [Release notes](https://github.com/opensearch-project/OpenSearch/releases)
- [Changelog](https://github.com/opensearch-project/OpenSearch/blob/main/CHANGELOG.md)
- [Commits](https://github.com/opensearch-project/OpenSearch/commits/2.18.0)

---
updated-dependencies:
- dependency-name: org.opensearch:opensearch-core
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <[email protected]>

buildSrc/src/testKit/thirdPartyAudit/build.gradle

@@ -40,7 +40,7 @@ repositories {
 }
 
 dependencies {
-  jdkJarHell 'org.opensearch:opensearch-core:current'
+  jdkJarHell 'org.opensearch:opensearch-core:2.18.0'
   compileOnly "org.${project.properties.compileOnlyGroup}:${project.properties.compileOnlyVersion}"
   implementation "org.${project.properties.compileGroup}:${project.properties.compileVersion}"
 }