RFR: 8345065: Cleanup DomainCombiner, SubjectDomainCombiner, Subject, and PrivilegedAction specifications [v2]

[Sean Mullan]

> A few additional changes should be made to the API specs for these classes .  These changes are documenting behavior of other APIs that has already been approved as part of JEP 486, so I don't think a CSR is necessary, but opinions on that are welcome.
> 
> The `DomainCombiner` and `SubjectDomainCombiner` classes contain wording about "inherited" and"privileged" `ProtectionDomain`s which is no longer  implemented, and so has been removed. The `PrivilegedAction` classes also contained wording about "privileged" computations which is no longer accurate. I also added an API note to these classes, similar to the ones in the `Permission` subclasses. Finally, I removed a couple of instances of "privileged work" from the `Subject` class which no longer applies.

Sean Mullan has updated the pull request incrementally with one additional commit since the last revision:

  Remove api notes.

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Changes:
  - all: https://git.openjdk.org/jdk/pull/22500/files
  - new: https://git.openjdk.org/jdk/pull/22500/files/7d26f8dc..24d4e81c

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=22500&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=22500&range=00-01

  Stats: 8 lines in 2 files changed: 0 ins; 8 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/22500.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/22500/head:pull/22500

PR: https://git.openjdk.org/jdk/pull/22500