RFR: JDK-8316629: j.text.DateFormatSymbols setZoneStrings() exception is unhelpful

[Justin Lu]

Please review this PR, which updates the exception message for java.text.DateFormatSymbols.setZoneStrings

`setZoneStrings()` takes a multi dimensional array as input. If any row does not have a length of at least 5, an _IllegalArgumentException_ is thrown. The exception should indicate why it was thrown.

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Commit messages:
 - init

Changes: https://git.openjdk.org/jdk/pull/15849/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=15849&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8316629
  Stats: 2 lines in 1 file changed: 1 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/15849.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/15849/head:pull/15849

PR: https://git.openjdk.org/jdk/pull/15849