RFR 8153038: The set of jlink plugins enabled by default should be the same via CLI or jlink API

[Sundararajan Athijegannathan]

Please review http://cr.openjdk.java.net/~sundar/8153038/webrev.00/ for 
https://bugs.openjdk.java.net/browse/JDK-8153038

PS. Pre-existing IntegrationTest.java test already checks the Jlink API 
code path [so, no new test added].

Thanks,
-Sundar