RFR: 8319444: Unhelpful failure output in TestLegalNotices

[Liam Miller-Cushon]

Please consider this fix for [JDK-8319444: Unhelpful failure output in TestLegalNotices](https://bugs.openjdk.org/browse/JDK-8319444), which improves test output for failing subtests.

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

Commit messages:
 - 8319444: Unhelpful failure output in TestLegalNotices

Changes: https://git.openjdk.org/jdk/pull/16507/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=16507&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8319444
  Stats: 3 lines in 1 file changed: 2 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/16507.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/16507/head:pull/16507

PR: https://git.openjdk.org/jdk/pull/16507