RFR: 8376218: Improve KeyUtil::getKeySize coverage

[Mikhail Yankelevich]

Improving `public static final int getKeySize(AlgorithmParameters parameters)` coverage

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Commit messages:
 - JDK-8376218: Improve KeyUtil::getKeySize coverage

Changes: https://git.openjdk.org/jdk/pull/29389/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=29389&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8376218
  Stats: 136 lines in 1 file changed: 136 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/29389.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/29389/head:pull/29389

PR: https://git.openjdk.org/jdk/pull/29389