RFR: 7539: JDP Tests failing in VPN environments [v6]

[Johannes Bechberger]

> Only run broadcasting related tests when supported.
> Tested on Mac M1 with and without VPN.

Johannes Bechberger has refreshed the contents of this pull request, and previous commits have been removed. The incremental views will show differences compared to the previous content of the PR. The pull request contains one new commit since the last revision:

  Small fixes

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Changes:
  - all: https://git.openjdk.java.net/jmc/pull/369/files
  - new: https://git.openjdk.java.net/jmc/pull/369/files/67473e8c..e3d853db

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jmc&pr=369&range=05
 - incr: https://webrevs.openjdk.java.net/?repo=jmc&pr=369&range=04-05

  Stats: 2 lines in 1 file changed: 1 ins; 0 del; 1 mod
  Patch: https://git.openjdk.java.net/jmc/pull/369.diff
  Fetch: git fetch https://git.openjdk.java.net/jmc pull/369/head:pull/369

PR: https://git.openjdk.java.net/jmc/pull/369