[jdk21u-dev] RFR: 8370492: [Linux] Update cpu shares to cpu.weight mapping function [v3]

[SendaoYan]

> Hi all,
> 
> This pull request contains a backport of commit [5d65c23c](https://github.com/openjdk/jdk/commit/5d65c23cd99b72527dcfab9eb6da9510e7dc6330) from the [openjdk/jdk](https://git.openjdk.org/jdk) repository.
> 
> The commit being backported was authored by Severin Gehwolf on 14 Nov 2025 and was reviewed by Casper Norrbin, Albert Mingkun Yang and SendaoYan.
> 
> Thanks!

SendaoYan has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains three additional commits since the last revision:

 - Merge branch 'openjdk:master' into backport-sendaoYan-5d65c23c-master
 - Merge branch 'openjdk:master' into backport-sendaoYan-5d65c23c-master
 - Backport 5d65c23cd99b72527dcfab9eb6da9510e7dc6330

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

Changes:
  - all: https://git.openjdk.org/jdk21u-dev/pull/2512/files
  - new: https://git.openjdk.org/jdk21u-dev/pull/2512/files/3d3cb870..cff68e34

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk21u-dev&pr=2512&range=02
 - incr: https://webrevs.openjdk.org/?repo=jdk21u-dev&pr=2512&range=01-02

  Stats: 7567 lines in 174 files changed: 5114 ins; 794 del; 1659 mod
  Patch: https://git.openjdk.org/jdk21u-dev/pull/2512.diff
  Fetch: git fetch https://git.openjdk.org/jdk21u-dev.git pull/2512/head:pull/2512

PR: https://git.openjdk.org/jdk21u-dev/pull/2512