Use standard Jenkinsfile

The custom Jenkinsfile has not detected any issues since it was first
created.  Maintaining the version list is a distraction.  Simpler is
better.

Jenkinsfile

@@ -1,35 +1,3 @@
-#!groovy
-
-import java.util.Collections
-
-if (env.JENKINS_URL.contains('markwaite.net')) {
-    // Valid Jenkins versions for markwaite.net test
-    def testJenkinsVersions = [ '2.479.1', '2.479.2', '2.479.3', '2.484', '2.485', '2.486', '2.487', '2.488', '2.489', '2.490', '2.491', '2.492']
-    Collections.shuffle(testJenkinsVersions)
-
-    // build with randomized Jenkins versions
-    subsetConfiguration = [
-
-                        // Intel Linux is labeled as 'linux' for legacy reasons
-                        // Linux first for coverage report on ci.jenkins.io
-                        [ jdk: 21, platform: 'linux',                                    ],
-                        [ jdk: 17, platform: 'linux',    jenkins: testJenkinsVersions[0] ],
-
-                        // Windows
-                        [ jdk: 17,  platform: 'windows', jenkins: testJenkinsVersions[1] ],
-
-                        // s390x label is also Linux
-                        [ jdk: 17, platform: 's390x',    jenkins: testJenkinsVersions[2] ],
-                        [ jdk: 21, platform: 's390x',    jenkins: testJenkinsVersions[3] ],
-                      ]
-
-    // Use advanced buildPlugin on markwaite.net
-    buildPlugin(configurations: subsetConfiguration, failFast: false, forkCount: '1C')
-    return
-}
-
-// Use simple buildPlugin elsewhere
-
 /*
  See the documentation for more options:
  https://github.com/jenkins-infra/pipeline-library/