Add 21 and 22 as supported versions in external tests

[llxia]

related: #4949

[llxia]

Grinder
build_image passed. The job failed at a later stage for something else that is not related to this PR.

00:01:12.822  build_image:
00:01:12.823       [echo] Executing external.sh --build --dir criu-ubi-portable-checkpoint --tag nightly --version 21 --impl openj9 --base_docker_registry_dir 'ubi8-with-criu/linux_ppc-64_le-ubi8-criu' --docker_registry_url docker-na.artifactory.swg-devops.com/sys-rt-docker-local --docker_args -v /home/jenkins/workspace/Grinder/jdkbinary/j2sdk-image:/opt/java/openjdk 
00:01:12.823       [exec] The test here is criu-ubi-portable-checkpoint
00:01:12.823       [exec] The directory in the external.sh is criu-ubi-portable-checkpoint
00:01:12.823       [exec] DOCKERIMAGE_TAG nightly has been recognized.
00:01:12.823       [exec] build_image.sh criu-ubi-portable-checkpoint 21 openj9 ubi jdk full linux_x86-64 ubi8-with-criu/linux_ppc-64_le-ubi8-criu 0 
00:01:12.823       [exec] /home/jenkins/workspace/Grinder/aqa-tests/external
00:01:12.823       [exec] 
00:01:12.823       [exec] Writing /home/jenkins/workspace/Grinder/jvmtest/external/criu-ubi-portable-checkpoint/dockerfile/21/jdk/ubi/Dockerfile.openj9.full ... done
00:01:12.823       [exec] 
00:01:12.823       [exec] The test in the build_image() function is criu-ubi-portable-checkpoint

[JasonFengJ9]

LGTM