[jdk21u-dev] RFR: 8303959: tools/jpackage/share/RuntimePackageTest.java fails with java.lang.AssertionError missing files

[Goetz Lindenmaier]

I backport this for parity with 21.0.4-oracle.

-------------

Commit messages:
 - Backport 5a6aa569aa279141193038dc2e61e18a8b24bc11

Changes: https://git.openjdk.org/jdk21u-dev/pull/485/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk21u-dev&pr=485&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8303959
  Stats: 22 lines in 1 file changed: 18 ins; 1 del; 3 mod
  Patch: https://git.openjdk.org/jdk21u-dev/pull/485.diff
  Fetch: git fetch https://git.openjdk.org/jdk21u-dev.git pull/485/head:pull/485

PR: https://git.openjdk.org/jdk21u-dev/pull/485