jtreg nightly build version change

[Martijn Verburg]

Hi all,

https://adopt-openjdk.ci.cloudbees.com/job/jtreg/lastSuccessfulBuild/artifact/now
produces a Maven compatible 5.0.0-SNAPSHOT version of jtreg.

This was to make the download and install for the Virtual Machines we're
producing for the build-farm as well as making jtreg Maven repo compatible.

IIRC jtreg was last released as version 4.3? Hopefully 5.0.0 is the next
logical number.

Probably needs a conversation about how to deal with versioning and if
jtreg can be uploaded to Maven Central or not (any legal barriers?).

Cheers,
Martijn