RFR: 8299237: add ArraysSupport.newLength test to a test group

[Stuart Marks]

This test isn't part of any test group, so it isn't being run regularly! I'm adding it to the jdk_util_other test group.

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Commit messages:
 - Add jdk/internal/util to jdk_util_other test group

Changes: https://git.openjdk.org/jdk/pull/11769/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=11769&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8299237
  Stats: 1 line in 1 file changed: 1 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/11769.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/11769/head:pull/11769

PR: https://git.openjdk.org/jdk/pull/11769