RFR: 8337641: G1: Remove unused G1CollectedHeap::alloc_highest_free_region

[Thomas Schatzl]

On Thu, 1 Aug 2024 07:39:31 GMT, Albert Mingkun Yang <ayang at openjdk.org> wrote:

> Trivial removing dead code.

`G1HeapRegionManager::find_highest_free()` can also be removed.

-------------

Changes requested by tschatzl (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/20415#pullrequestreview-2211909772