[Rollup] Replace RollupIT with a ESRestTestCase version (elastic#31977)

The old RollupIT was a node IT, an flaky for a number of reasons.
This new version is an ESRestTestCase and should be a little more robust.

This was added to the multi-node QA tests as that seemed like the most
appropriate location.  It didn't seem necessary to create a whole new
QA module.

Note: The only test that was ported was the "Big" test for validating
a larger dataset.  The rest of the tests are represented in existing
yaml tests.

Closes elastic#31258
Closes elastic#30232
Related to elastic#30290

Author: polyfractal

x-pack/plugin/rollup/build.gradle

@@ -1,6 +1,3 @@
-import com.carrotsearch.gradle.junit4.RandomizedTestingTask
-import org.elasticsearch.gradle.BuildPlugin
-
 evaluationDependsOn(xpackModule('core'))
 
 apply plugin: 'elasticsearch.esplugin'
@@ -23,33 +20,8 @@ dependencies {
     testCompile project(path: xpackModule('core'), configuration: 'testArtifacts')
 }
 
-dependencyLicenses {
-    ignoreSha 'x-pack-core'
-}
-
 run {
     plugin xpackModule('core')
 }
 
 integTest.enabled = false
-
-
-// Instead we create a separate task to run the
-// tests based on ESIntegTestCase
-task internalClusterTest(type: RandomizedTestingTask,
-        group: JavaBasePlugin.VERIFICATION_GROUP,
-        description: 'Multi-node tests',
-        dependsOn: test.dependsOn) {
-    configure(BuildPlugin.commonTestConfig(project))
-    classpath = project.test.classpath
-    testClassesDirs = project.test.testClassesDirs
-    include '**/*IT.class'
-    systemProperty 'es.set.netty.runtime.available.processors', 'false'
-}
-check.dependsOn internalClusterTest
-internalClusterTest.mustRunAfter test
-
-// also add an "alias" task to make typing on the command line easier task icTest {
-task icTest {
-    dependsOn internalClusterTest
-}