RFR: JDK-8266254: Update to use jtreg 6

[Naoto Sato]

On Wed, 2 Jun 2021 16:13:48 GMT, Jonathan Gibbons <jjg at openjdk.org> wrote:

> Please review the change to update to using jtreg 6. 
> 
> The primary change is to the jib-profiles.js file, which specifies the version of jtreg to use, for those systems that rely on this file. In addition, the `requiredVersion` has been updated in the various `TEST.ROOT` files.
> 
> All the tests that could be updated ahead of time have been updated. There are a few tests remaining that need to be done at this time, because of the change in the module name for TestNG 7.3. It changed from a default of `testng` to and explicit `org.testng`.

Some of the modified files have copyright year left unchanged. `2021` needs to be appended.

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PR: https://git.openjdk.java.net/jdk/pull/4315