[jdk21u-dev] RFR: 8288989: Make tests not depend on the source code

[Goetz Lindenmaier]

I backport this for parity with 21.0.4-oracle.

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Commit messages:
 - Backport 2838a916ab98cb0152f8b1e3f96eccca198af5e9

Changes: https://git.openjdk.org/jdk21u-dev/pull/373/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk21u-dev&pr=373&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8288989
  Stats: 11 lines in 2 files changed: 8 ins; 0 del; 3 mod
  Patch: https://git.openjdk.org/jdk21u-dev/pull/373.diff
  Fetch: git fetch https://git.openjdk.org/jdk21u-dev.git pull/373/head:pull/373

PR: https://git.openjdk.org/jdk21u-dev/pull/373