RFR: 8351689: -Xshare:dump with default classlist fails on static JDK

[Jiangli Zhou]

Please review the change to use `Arguments::get_java_home` to resolve the default classlist path. This avoids the complication of walking up the directory from libjvm and the subtle handling for '/lib' dir, which is what `MetaspaceShared::get_default_classlist` needs to do. This fixes the failure on static JDK for running `-Xshare:dump` with the default classlist. Please see more details in https://bugs.openjdk.org/browse/JDK-8351689.

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Commit messages:
 - Resolve Whitespace error.
 - Simplify get default classlist.

Changes: https://git.openjdk.org/jdk/pull/24000/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=24000&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8351689
  Stats: 34 lines in 2 files changed: 4 ins; 28 del; 2 mod
  Patch: https://git.openjdk.org/jdk/pull/24000.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/24000/head:pull/24000

PR: https://git.openjdk.org/jdk/pull/24000