Fix external container-based tests JDK_VERSION setting

[LongyuZhang]

In several external test test.sh file, we have the command to unset JDK_VERSION and use auto-detect ( code link ), this was because this parameters were not passed correctly. We can further improve it by correcting the passed JDK_VERSION parameter.

• In external.sh and build_image.sh files (maybe also other files), check where this parameter was not passed correctly, fix it.
• Then for all external tests, remove JDK_VERSION unset command as it will not be needed.