[Test] Use version range for elasticsearch-java (elastic#127510) (elastic#127705)

Snapshot builds of elasticsearch-java are no longer available.
Using the current major highest version should be safe according to the
compatibility guarantees described on https://github.com/elastic/elasticsearch-java?tab=readme-ov-file#compatibility

Additionally, reorganize Maven repository configuration in build.gradle
Repo https://snapshots.elastic.co/maven/ is no longer needed in a
composite build. Previously it was only used to provide snapshot version
 of `elasticsearch-java` client which is no longer available in snapshot
  version. We keep the https://snapshots.elastic.co/maven/ repo to be
  used when for non-composite builds when any other dependencies
  snapshot versions can be fetched.

Author: jozala

plugins/examples/build.gradle

@@ -22,22 +22,16 @@ subprojects {
 
   repositories {
     // Only necessary when building plugins against SNAPSHOT versions of Elasticsearch
-    maven {
-      url = 'https://snapshots.elastic.co/maven/'
-      mavenContent {
-        if (gradle.includedBuilds) {
-          // When building in a composite, restrict this to only resolve the Java REST client
-          includeModule 'co.elastic.clients', 'elasticsearch-java'
-        }
-      }
-    }
     if (gradle.includedBuilds.isEmpty()) {
       maven {
         url = "https://artifacts-snapshot.elastic.co/elasticsearch/${elasticsearchVersion}/maven"
         mavenContent {
           includeModule 'org.elasticsearch', 'elasticsearch'
         }
       }
+      maven {
+        url = 'https://snapshots.elastic.co/maven/'
+      }
     }
 
     // Same for Lucene, add the snapshot repo based on the currently used Lucene version

plugins/examples/security-authorization-engine/build.gradle

@@ -16,7 +16,7 @@ dependencies {
   testImplementation "org.elasticsearch.plugin:x-pack-core:${elasticsearchVersion}"
   javaRestTestImplementation "org.elasticsearch.plugin:x-pack-core:${elasticsearchVersion}"
   javaRestTestImplementation "org.apache.logging.log4j:log4j-core:${log4jVersion}"
-  javaRestTestImplementation("co.elastic.clients:elasticsearch-java:${elasticsearchVersion}")
+  javaRestTestImplementation "co.elastic.clients:elasticsearch-java:[8.0,9.0)"
   javaRestTestImplementation "org.elasticsearch.client:elasticsearch-rest-client:${elasticsearchVersion}"
   javaRestTestImplementation 'com.fasterxml.jackson.core:jackson-databind:2.12.3'
   javaRestTestImplementation "org.elasticsearch.test:framework:${elasticsearchVersion}"