[jdk17u] RFR: 8269897: Shenandoah: Resolve UNKNOWN access strength, where possible

[Aleksey Shipilev]

Clean backport to fix a serious Shenandoah bug.

Additional testing:
 - [x] `jcstress` now passes
 - [x] `hotspot_gc_shenandoah` passes
 - [x] `tier1` with `-XX:+UseShenandoahGC` passes
 - [x] `tier2` with `-XX:+UseShenandoahGC` passes

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Commit messages:
 - Backport 7ac08161a8b2080ed054bc00a30d6f694ece4df3

Changes: https://git.openjdk.java.net/jdk17u/pull/37/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk17u&pr=37&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8269897
  Stats: 116 lines in 3 files changed: 49 ins; 33 del; 34 mod
  Patch: https://git.openjdk.java.net/jdk17u/pull/37.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk17u pull/37/head:pull/37

PR: https://git.openjdk.java.net/jdk17u/pull/37