RFR: 8343958: Remove security manager impl in java.lang.Process and java.lang.Runtime.exec [v4]

[Roger Riggs]

> Refactor removing the dependencies on SecurityManager, doPrivileged, and AccessController.

Roger Riggs has updated the pull request incrementally with one additional commit since the last revision:

  Revert unnecessary copyright change in ProcessEnvironment.java.
  Fix code style in ProcessImpl
  Drop unneeded suppress warnings.
  Remove obsolete @throws SecurityExceptions

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Changes:
  - all: https://git.openjdk.org/jdk/pull/22024/files
  - new: https://git.openjdk.org/jdk/pull/22024/files/4535e388..accc6df3

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=22024&range=03
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=22024&range=02-03

  Stats: 8 lines in 3 files changed: 0 ins; 6 del; 2 mod
  Patch: https://git.openjdk.org/jdk/pull/22024.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/22024/head:pull/22024

PR: https://git.openjdk.org/jdk/pull/22024