RFR: 8304696: Duplicate class names in dynamicArchive tests can lead to test failure [v2]

[Calvin Cheung]

> To avoid duplicate class name `MyShutdown`, the fix is to change the `MyShutdown` class name for the LambdaProxyDuringShutdown.java test to `ShutdownHelper`.
> 
> Tested manually by running the LInkClassTest.java and LambdaProxyDuringShutdown.java tests serially on linux-x64.
> Also ran tiers 1 and 3 testing.

Calvin Cheung has updated the pull request incrementally with one additional commit since the last revision:

  @iklam comments

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Changes:
  - all: https://git.openjdk.org/jdk/pull/13542/files
  - new: https://git.openjdk.org/jdk/pull/13542/files/6fd57873..16652c98

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=13542&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=13542&range=00-01

  Stats: 14 lines in 4 files changed: 2 ins; 2 del; 10 mod
  Patch: https://git.openjdk.org/jdk/pull/13542.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/13542/head:pull/13542

PR: https://git.openjdk.org/jdk/pull/13542