[jdk17u] RFR: 8261495: Shenandoah: reconsider update references memory ordering

[Aleksey Shipilev]

Clean backport to improve Shenandoah performance.

Additional testing: 
 - [x] Linux x86_64 fastdebug `hotspot_gc_shenandoah`
 - [x] Linux x86_64 fastdebug `tier1`

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Commit messages:
 - Backport a96012a7afce6678125d3fb537f2433642953315

Changes: https://git.openjdk.java.net/jdk17u/pull/254/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk17u&pr=254&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8261495
  Stats: 130 lines in 7 files changed: 93 ins; 15 del; 22 mod
  Patch: https://git.openjdk.java.net/jdk17u/pull/254.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk17u pull/254/head:pull/254

PR: https://git.openjdk.java.net/jdk17u/pull/254