RFR: 8365237: Remove unused SoftRefPolicy::_all_soft_refs_clear [v2]

[Albert Mingkun Yang]

> Trivial removing effectively dead code.
> 
> Test: tier1

Albert Mingkun Yang has updated the pull request incrementally with one additional commit since the last revision:

  review

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Changes:
  - all: https://git.openjdk.org/jdk/pull/26722/files
  - new: https://git.openjdk.org/jdk/pull/26722/files/7a8a54ad..c8447f7a

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=26722&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=26722&range=00-01

  Stats: 1 line in 1 file changed: 0 ins; 1 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/26722.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/26722/head:pull/26722

PR: https://git.openjdk.org/jdk/pull/26722