RFR: 7903624: Use openjdk.org instead of openjdk.java.net

[Magnus Ihse Bursie]

We should use openjdk.org instead of openjdk.java.net.

This bug was triggered by the fact that git.openjdk.java.net had problem resolving properly for GitHub Actions in the build script (and the theory is that git.openjdk.org would work better), but this should be fixed nevertheless.

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Commit messages:
 - 7903624: Use openjdk.org instead of openjdk.java.net

Changes: https://git.openjdk.org/jtreg/pull/180/files
 Webrev: https://webrevs.openjdk.org/?repo=jtreg&pr=180&range=00
  Issue: https://bugs.openjdk.org/browse/CODETOOLS-7903624
  Stats: 18 lines in 10 files changed: 0 ins; 0 del; 18 mod
  Patch: https://git.openjdk.org/jtreg/pull/180.diff
  Fetch: git fetch https://git.openjdk.org/jtreg.git pull/180/head:pull/180

PR: https://git.openjdk.org/jtreg/pull/180