[jdk25u-dev] RFR: 8370492: [Linux] Update cpu shares to cpu.weight mapping function

[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!

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Commit messages:
 - Backport 5d65c23cd99b72527dcfab9eb6da9510e7dc6330

Changes: https://git.openjdk.org/jdk25u-dev/pull/72/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk25u-dev&pr=72&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8370492
  Stats: 107 lines in 4 files changed: 90 ins; 0 del; 17 mod
  Patch: https://git.openjdk.org/jdk25u-dev/pull/72.diff
  Fetch: git fetch https://git.openjdk.org/jdk25u-dev.git pull/72/head:pull/72

PR: https://git.openjdk.org/jdk25u-dev/pull/72