ci: Move CircleCI to next-gen convenience images

https://discuss.circleci.com/t/legacy-convenience-image-deprecation/41034

Author: flaix

.circleci/config.yml

@@ -27,19 +27,19 @@ version: 2.1
 jobs:
   buildJ8:
     docker:
-      - image: circleci/openjdk:8-jdk
+      - image: cimg/openjdk:8-jdk
 
     <<: *gbsteps
 
   buildJ9:
     docker:
-      - image: circleci/openjdk:9-jdk
+      - image: cimg/openjdk:9-jdk
 
     <<: *gbsteps
 
   buildJ11:
     docker:
-      - image: circleci/openjdk:11-jdk
+      - image: cimg/openjdk:11-jdk
 
     <<: *gbsteps