Upgrade default base Docker image to UBI9 (#118068)

Default base Docker image UBI has been upgraded from version 8 to 9.

Author: jozala

build-tools-internal/src/main/java/org/elasticsearch/gradle/internal/DockerBase.java

@@ -13,8 +13,8 @@
  * This class models the different Docker base images that are used to build Docker distributions of Elasticsearch.
  */
 public enum DockerBase {
-    // "latest" here is intentional, since the image name specifies "8"
-    DEFAULT("docker.elastic.co/ubi8/ubi-minimal:latest", "", "microdnf"),
+    // "latest" here is intentional, since the image name specifies "9"
+    DEFAULT("docker.elastic.co/ubi9/ubi-minimal:latest", "", "microdnf"),
 
     // The Iron Bank base image is UBI (albeit hardened), but we are required to parameterize the Docker build
     IRON_BANK("${BASE_REGISTRY}/${BASE_IMAGE}:${BASE_TAG}", "-ironbank", "yum"),

distribution/build.gradle

@@ -70,10 +70,10 @@ tasks.register("generateDependenciesReport", ConcatFilesTask) {
   // Explicitly add the dependency on the RHEL UBI Docker base image
   String[] rhelUbiFields = [
     'Red Hat Universal Base Image minimal',
-    '8',
-    'https://catalog.redhat.com/software/containers/ubi8/ubi-minimal/5c359a62bed8bd75a2c3fba8',
+    '9',
+    'https://catalog.redhat.com/software/containers/ubi9-minimal/61832888c0d15aff4912fe0d',
     'Custom;https://www.redhat.com/licenses/EULA_Red_Hat_Universal_Base_Image_English_20190422.pdf',
-    'https://oss-dependencies.elastic.co/red-hat-universal-base-image-minimal/8/ubi-minimal-8-source.tar.gz'
+    'https://oss-dependencies.elastic.co/red-hat-universal-base-image-minimal/9/ubi-minimal-9-source.tar.gz'
   ]
   additionalLines << rhelUbiFields.join(',')
 }