[jdk17u-dev] RFR: 8289798: Update to use jtreg 7

[Goetz Lindenmaier]

I want to backport this on the patch to jtreg 7.2.

I had to move the edit of lib-tests.m4 to toolchain.m4

All the others I resolved because we skipped the step to 6.1.

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Commit messages:
 - Backport 1ee59adcfead2128316556121c1711d308c7ea01

Changes: https://git.openjdk.org/jdk17u-dev/pull/1595/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk17u-dev&pr=1595&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8289798
  Stats: 12 lines in 8 files changed: 0 ins; 0 del; 12 mod
  Patch: https://git.openjdk.org/jdk17u-dev/pull/1595.diff
  Fetch: git fetch https://git.openjdk.org/jdk17u-dev.git pull/1595/head:pull/1595

PR: https://git.openjdk.org/jdk17u-dev/pull/1595