Reduce Jenkinsfile diffs to archetype

Use the Jenkins plugin archetype as much as possible as we can so that
the differences to the archetype are clear and intentionally used.

Tests with Java 21 on Linux and Java 17 on Windows.  Accepts that tests
on Java 11 are redundant since we've not detected relevant issues that
are specific to Java 11.

Confirmed that tests pass on Linux with Java 17 and Java 21.

Rely on ci.jenkins.io to test Windows.

Does not include forkCount setting because it does not improve test
performance on this repository.

Jenkinsfile

@@ -1,15 +1,10 @@
-/* `buildPlugin` step provided by: https://github.com/jenkins-infra/pipeline-library */
+/*
+ See the documentation for more options:
+ https://github.com/jenkins-infra/pipeline-library/
+*/
 buildPlugin(
-  // Run a JVM per core in tests
-  forkCount: '1C',
-  // Container agents start faster and are easier to administer
-  useContainerAgent: true,
-  // Show failures on all configurations
-  failFast: false,
-  // Test Java 11, 17, and 21
+  useContainerAgent: true, // Set to `false` if you need to use Docker for containerized tests
   configurations: [
-    [platform: 'linux',   jdk: '17'],
-    [platform: 'linux',   jdk: '21', jenkins: '2.414'],
-    [platform: 'windows', jdk: '11']
-  ]
-)
+    [platform: 'linux', jdk: 21],
+    [platform: 'windows', jdk: 17],
+])