[jdk21u-dev] RFR: 8365098: make/RunTests.gmk generates a wrong path to test artifacts on Alpine

[Roman Marchenko]

This is backport of "[JDK-8365098](https://bugs.openjdk.org/browse/JDK-8365098) make/RunTests.gmk generates a wrong path to test artifacts on Alpine" as JDK21 tests have the same issue on Alpine - generate a wrong path to test artifacts.

Build system fix. Clean backport.

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Commit messages:
 - 8365098: make/RunTests.gmk generates a wrong path to test artifacts on Alpine

Changes: https://git.openjdk.org/jdk21u-dev/pull/2237/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk21u-dev&pr=2237&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8365098
  Stats: 3 lines in 1 file changed: 0 ins; 0 del; 3 mod
  Patch: https://git.openjdk.org/jdk21u-dev/pull/2237.diff
  Fetch: git fetch https://git.openjdk.org/jdk21u-dev.git pull/2237/head:pull/2237

PR: https://git.openjdk.org/jdk21u-dev/pull/2237