RFR: 8301768: G1: Remove unimplemented HeapRegionRemSet::split_card

[Albert Mingkun Yang]

On Fri, 3 Feb 2023 14:16:41 GMT, Albert Mingkun Yang <ayang at openjdk.org> wrote:

> Trivial removing dead code.

Thanks for the review.

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PR: https://git.openjdk.org/jdk/pull/12408