[jdk11u-dev] RFR: 8318154: Improve stability of WheelModifier.java test

[Andrew Lu]

I backport this for parity with 11.0.23-oracle.

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Commit messages:
 - Backport 668d4b077f260a30a90842a01b38a9cf6718d418

Changes: https://git.openjdk.org/jdk11u-dev/pull/2459/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk11u-dev&pr=2459&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8318154
  Stats: 25 lines in 1 file changed: 16 ins; 1 del; 8 mod
  Patch: https://git.openjdk.org/jdk11u-dev/pull/2459.diff
  Fetch: git fetch https://git.openjdk.org/jdk11u-dev.git pull/2459/head:pull/2459

PR: https://git.openjdk.org/jdk11u-dev/pull/2459