Fix openjdk.test.jck build script

[Mesbah-Alam]

• Adds logic to remove any possible leading or trailing spaces from ${jck_runtimes_src_dir}

Signed-off-by: Mesbah_Alam@ca.ibm.com Mesbah_Alam@ca.ibm.com

[Mesbah-Alam]

Test with a system test target

• Linux: Internal-Grinder/11993 (with OpenJ9 JDK16)
• Windows: https://ci.adoptopenjdk.net/view/Test_grinder/job/Grinder/4647/console (with OpenJ9 JDK11)
• Mac : https://ci.adoptopenjdk.net/view/Test_grinder/job/Grinder/4648/console (with OpenJ9 JDK11)

Test with a JCK target:

• With OpenJ9 JDK16 : Internal-Grinder/11994
• With OpenJ9 JDK8 Internal-Grinder/11998
• With OpenJ9 JDK11 Internal-Grinder/11999

[Mesbah-Alam]

Closing this PR without merging as the issue is now dealt wth https://github.com/AdoptOpenJDK/openjdk-tests/pull/2052

For more details, see backlog/issues/414