Skip dragonwell feature test target when the test jdk is dragonwell standard version

[sendaoYan]

Skip dragonwell feature test target when the test jdk is dragonwell standard version. When the test jdk is dragonwell standard version, export TEST_FLAG=Dragonwell_Standard

Fixes: #3911

Signed-off-by: sendaoYan [email protected]

[llxia]

Just a heads up, as TEST_FLAG becomes more popular, we will set up a naming convention for it soon. (Suggestions are welcome!) The current TEST_FLAG value may or may not need to be adjusted by then.