[jdk21u-dev] RFR: 8333398: Uncomment the commented test in test/jdk/java/util/jar/JarFile/mrjar/MultiReleaseJarAPI.java

[Amos Shi]

Backport of [JDK-8333398](https://bugs.openjdk.org/browse/JDK-8333398)

Testing
- Local: Test passed
  - `MultiReleaseJarAPI.java`: Test results: passed: 1
- Pipeline: 
- Testing Machine:

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Commit messages:
 - Backport d230b30353f59135287436b09949b80e9fd73a93

Changes: https://git.openjdk.org/jdk21u-dev/pull/759/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk21u-dev&pr=759&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8333398
  Stats: 5 lines in 1 file changed: 0 ins; 3 del; 2 mod
  Patch: https://git.openjdk.org/jdk21u-dev/pull/759.diff
  Fetch: git fetch https://git.openjdk.org/jdk21u-dev.git pull/759/head:pull/759

PR: https://git.openjdk.org/jdk21u-dev/pull/759