RFR: 8371607: Remove GCSharedStringsDuringDumpWb.java after JDK-8362561

[Paul Hübner]

Hi all,

[JDK-8362561](https://bugs.openjdk.org/browse/JDK-8362561) removed `runtime/cds/appcds/javaldr/GCSharedStringsDuringDump.java` which was the only place where `GCSharedStringsDuringDumpWb.java` was used. Therefore, `GCSharedStringsDuringDumpWb.java` should be cleaned up.

Testing: tiers 1-3 Linux (x64, AArch64), macOS (x64, AArch64), Windows (x64).

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Commit messages:
 - Remove class.

Changes: https://git.openjdk.org/jdk/pull/28300/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=28300&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8371607
  Stats: 45 lines in 1 file changed: 0 ins; 45 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/28300.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/28300/head:pull/28300

PR: https://git.openjdk.org/jdk/pull/28300