RFR: 8365620: Using enhanced switch in MethodHandleDesc

[Shaojin Wen]

In MethodHandleDesc, the `ofField` method uses enhanced switch, while the `of` and `ofMethod` methods use traditional switch. The same class should have a unified style.

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Commit messages:
 - from @liach
 - enhanced switch

Changes: https://git.openjdk.org/jdk/pull/26769/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=26769&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8365620
  Stats: 26 lines in 1 file changed: 0 ins; 14 del; 12 mod
  Patch: https://git.openjdk.org/jdk/pull/26769.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/26769/head:pull/26769

PR: https://git.openjdk.org/jdk/pull/26769