REST API compat testing - remove the requirement for default distro (#71119)

Originally much of the REST API compatibility code was to live in
x-pack. However, some design changes has removed this requirements
and there is no longer a need to explicitly use the default distribution
for REST API compatibility testing.

Author: jakelandis

buildSrc/src/integTest/groovy/org/elasticsearch/gradle/YamlRestCompatTestPluginFuncTest.groovy

@@ -73,9 +73,6 @@ class YamlRestCompatTestPluginFuncTest extends AbstractRestResourcesFuncTest {
 
             // avoids a dependency problem in this test, the distribution in use here is inconsequential to the test
             import org.elasticsearch.gradle.testclusters.TestDistribution;
-            testClusters {
-              yamlRestCompatTest.setTestDistribution(TestDistribution.INTEG_TEST)
-            }
 
             dependencies {
                yamlRestTestImplementation "junit:junit:4.12"
@@ -198,10 +195,7 @@ class YamlRestCompatTestPluginFuncTest extends AbstractRestResourcesFuncTest {
 
             // avoids a dependency problem in this test, the distribution in use here is inconsequential to the test
             import org.elasticsearch.gradle.testclusters.TestDistribution;
-            testClusters {
-              yamlRestCompatTest.setTestDistribution(TestDistribution.INTEG_TEST)
-            }
-
+     
             dependencies {
                yamlRestTestImplementation "junit:junit:4.12"
             }

buildSrc/src/main/java/org/elasticsearch/gradle/internal/rest/compat/YamlRestCompatTestPlugin.java

@@ -19,9 +19,7 @@
 import org.elasticsearch.gradle.test.rest.RestResourcesPlugin;
 import org.elasticsearch.gradle.test.rest.RestTestUtil;
 import org.elasticsearch.gradle.test.rest.YamlRestTestPlugin;
-import org.elasticsearch.gradle.testclusters.ElasticsearchCluster;
 import org.elasticsearch.gradle.testclusters.TestClustersPlugin;
-import org.elasticsearch.gradle.testclusters.TestDistribution;
 import org.elasticsearch.gradle.util.GradleUtils;
 import org.gradle.api.Plugin;
 import org.gradle.api.Project;
@@ -39,7 +37,6 @@
 import java.nio.file.Path;
 import java.util.Map;
 
-import static org.elasticsearch.gradle.test.rest.RestTestUtil.createTestCluster;
 import static org.elasticsearch.gradle.test.rest.RestTestUtil.setupDependencies;
 
 /**
@@ -75,10 +72,6 @@ public void apply(Project project) {
         SourceSet yamlTestSourceSet = sourceSets.getByName(YamlRestTestPlugin.SOURCE_SET_NAME);
         GradleUtils.extendSourceSet(project, YamlRestTestPlugin.SOURCE_SET_NAME, SOURCE_SET_NAME);
 
-        // create the test cluster container, and always use the default distribution
-        ElasticsearchCluster testCluster = createTestCluster(project, yamlCompatTestSourceSet);
-        testCluster.setTestDistribution(TestDistribution.DEFAULT);
-
         // copy compatible rest specs
         Configuration bwcMinorConfig = project.getConfigurations().create("bwcMinor");
         Dependency bwcMinor = project.getDependencies().project(Map.of("path", ":distribution:bwc:minor", "configuration", "checkout"));