RFR: 8378759: Make ZipFile.CleanableResource.inflaterCache field final [v2]

[Eirik Bjørsnøs]

> Please review this cleanup PR where we simplify synchronization on ZipFile's inflater cache.
> 
> Currently, the `ZipFile.CleanableResource.inflaterCache` field is non-final, is used in synchronization and is set to `null` to indicate a closed inflater cache. This complicates the state considerations for synchronization, requiring double-checking that the cache does not close under us. Generally, correctness of synchronizing on a non-final field which can also be null is hard to reason about.
> 
> This PR marks the `inflaterCache` field as `final` and introduces a boolean flag field to model the closed state explicitly. This allows synchronization to be simplified, double-checking to be removed and the closed state to be more obvious. If we want the future ZipFile to be less mutable, this is one step in that direction.
> 
> Cleanup refactoring, `noreg-cleanup`

Eirik Bjørsnøs has updated the pull request incrementally with one additional commit since the last revision:

  Reduce memory retained by a closed ZipFile

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Changes:
  - all: https://git.openjdk.org/jdk/pull/29937/files
  - new: https://git.openjdk.org/jdk/pull/29937/files/a73afcae..6b9d8f98

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=29937&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=29937&range=00-01

  Stats: 4 lines in 1 file changed: 2 ins; 0 del; 2 mod
  Patch: https://git.openjdk.org/jdk/pull/29937.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/29937/head:pull/29937

PR: https://git.openjdk.org/jdk/pull/29937