RFR: 8298480: Remove unused KlassRemSet

[Albert Mingkun Yang]

On Fri, 9 Dec 2022 15:20:29 GMT, Albert Mingkun Yang <ayang at openjdk.org> wrote:

> Trivial removing of dead code.

Thanks for the review.

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PR: https://git.openjdk.org/jdk/pull/11611