GHA/windows: install OpenSSH-Windows manually for transparency

GHA/windows: install OpenSSH-Windows manually for transparency

To have the current latest version, and to avoid the stale, misleading
versions installed by Chocolatey. It also installs transparently, faster,
and making the source of the binaries clear. Install on drive `D:` for
best performance.

After much detective work it turns out that the OpenSSH Windows versions
installed by Chocolatey aren't what they seem:

- The latest pre-release named 9.5.0-beta20240403:
  https://community.chocolatey.org/packages/openssh/9.5.0-beta20240403
  is in reality 8.6.0.0p1-Beta from 2021-05-27:
  https://github.com/PowerShell/Win32-OpenSSH/releases/download/V8.6.0.0p1-Beta/OpenSSH-Win64.zip

- The latest "stable" version 8.0.0.1 is in reality:
  https://community.chocolatey.org/packages/openssh/8.0.0.1
  is in reality 8.0.0.0p1-Beta:
  https://github.com/PowerShell/Win32-OpenSSH/releases/download/v8.0.0.0p1-Beta/OpenSSH-Win64.zip

Ref: https://github.com/curl/curl/pull/16803#issuecomment-2746365654
Follow-up to 67a7775d1233d702964bff9a0a6b5b9fa036c47a #16704
Follow-up to 0ec72c1ef8d87a29bf2eaa5e36ab173147a4d015 #16672

Closes #16811