RFR: 8368975: Windows ProcessImpl.java has dead code [v3]

[Francesco Andreuzzi]

> Removal of dead code in the windows flavor of `ProcessImpl.java`. The removed branches can't be reached because `allowAmbiguousCommands` is known to be `false` in the `else` block.
> 
> Passes tier1 in GHA.

Francesco Andreuzzi has updated the pull request incrementally with one additional commit since the last revision:

  more dead code

-------------

Changes:
  - all: https://git.openjdk.org/jdk/pull/27945/files
  - new: https://git.openjdk.org/jdk/pull/27945/files/14cb9239..4a97ad4f

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=27945&range=02
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=27945&range=01-02

  Stats: 7 lines in 1 file changed: 0 ins; 7 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/27945.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/27945/head:pull/27945

PR: https://git.openjdk.org/jdk/pull/27945