Build CI images in parallel

Closes gh-18115

ci/pipeline.yml

@@ -144,18 +144,19 @@ jobs:
   plan:
   - get: ci-images-git-repo
     trigger: true
-  - put: spring-boot-ci-image
-    params:
-      build: ci-images-git-repo/ci/images
-      dockerfile: ci-images-git-repo/ci/images/spring-boot-ci-image/Dockerfile
-  - put: spring-boot-jdk11-ci-image
-    params:
-      build: ci-images-git-repo/ci/images
-      dockerfile: ci-images-git-repo/ci/images/spring-boot-jdk11-ci-image/Dockerfile
-  - put: spring-boot-jdk12-ci-image
-    params:
-      build: ci-images-git-repo/ci/images
-      dockerfile: ci-images-git-repo/ci/images/spring-boot-jdk12-ci-image/Dockerfile
+  - in_parallel:
+    - put: spring-boot-ci-image
+      params:
+        build: ci-images-git-repo/ci/images
+        dockerfile: ci-images-git-repo/ci/images/spring-boot-ci-image/Dockerfile
+    - put: spring-boot-jdk11-ci-image
+      params:
+        build: ci-images-git-repo/ci/images
+        dockerfile: ci-images-git-repo/ci/images/spring-boot-jdk11-ci-image/Dockerfile
+    - put: spring-boot-jdk12-ci-image
+      params:
+        build: ci-images-git-repo/ci/images
+        dockerfile: ci-images-git-repo/ci/images/spring-boot-jdk12-ci-image/Dockerfile
 - name: detect-jdk-updates
   plan:
   - get: git-repo