Repository: neovim
Issue: CI: orphan processes (tty-test) in Windows CI
Labels: platform:windows,test,job-control,ci

### Problem

Lots of orphan processes mentioned in Windows CI logs. Could this lead to instability or slower performance on Windows CI?

```
2023-01-16T08:32:59.9048237Z Cleaning up orphan processes
2023-01-16T08:32:59.9329053Z Terminate orphan process: pid (5444) (conhost)
2023-01-16T08:32:59.9389448Z Terminate orphan process: pid (3396) (cmd)
2023-01-16T08:32:59.9461038Z Terminate orphan process: pid (4268) (nvim)
2023-01-16T08:32:59.9531511Z Terminate orphan process: pid (1000) (nvim)
2023-01-16T08:32:59.9601955Z Terminate orphan process: pid (1940) (cmd)
2023-01-16T08:32:59.9676026Z Terminate orphan process: pid (1264) (nvim)
2023-01-16T08:32:59.9746930Z Terminate orphan process: pid (2568) (nvim)
2023-01-16T08:32:59.9799045Z Terminate orphan process: pid (3308) (cmd)
2023-01-16T08:32:59.9891301Z Terminate orphan process: pid (2952) (nvim)
2023-01-16T08:32:59.9961147Z Terminate orphan process: pid (5160) (nvim)
2023-01-16T08:33:00.0018248Z Terminate orphan process: pid (5844) (conhost)
2023-01-16T08:33:00.0079660Z Terminate orphan process: pid (4160) (conhost)
2023-01-16T08:33:00.0132098Z Terminate orphan process: pid (5092) (shell-test)
2023-01-16T08:33:00.0193207Z Terminate orphan process: pid (5816) (conhost)
2023-01-16T08:33:00.0251301Z Terminate orphan process: pid (772) (conhost)
2023-01-16T08:33:00.0309612Z Terminate orphan process: pid (2232) (conhost)
2023-01-16T08:33:00.0381139Z Terminate orphan process: pid (5896) (conhost)
2023-01-16T08:33:00.0444286Z Terminate orphan process: pid (4616) (tty-test)
2023-01-16T08:33:00.0503963Z Terminate orphan process: pid (2860) (conhost)
2023-01-16T08:33:00.0565332Z Terminate orphan process: pid (5452) (tty-test)
2023-01-16T08:33:00.0642620Z Terminate orphan process: pid (3128) (conhost)
2023-01-16T08:33:00.0704388Z Terminate orphan process: pid (3332) (tty-test)
2023-01-16T08:33:00.0763978Z Terminate orphan process: pid (2996) (conhost)
2023-01-16T08:33:00.0824184Z Terminate orphan process: pid (5620) (tty-test)
2023-01-16T08:33:00.0883577Z Terminate orphan process: pid (4272) (conhost)
2023-01-16T08:33:00.1021372Z Terminate orphan process: pid (5296) (tty-test)
2023-01-16T08:33:00.1084560Z Terminate orphan process: pid (2076) (conhost)
2023-01-16T08:33:00.1147136Z Terminate orphan process: pid (4100) (tty-test)
2023-01-16T08:33:00.1267498Z Terminate orphan process: pid (760) (conhost)
2023-01-16T08:33:00.1330970Z Terminate orphan process: pid (4012) (tty-test)
2023-01-16T08:33:00.1392988Z Terminate orphan process: pid (5752) (conhost)
2023-01-16T08:33:00.1456033Z Terminate orphan process: pid (2452) (tty-test)
2023-01-16T08:33:00.1522869Z Terminate orphan process: pid (4184) (conhost)
2023-01-16T08:33:00.1731516Z Terminate orphan process: pid (628) (tty-test)
2023-01-16T08:33:00.1791333Z Terminate orphan process: pid (2792) (conhost)
2023-01-16T08:33:00.1851797Z Terminate orphan process: pid (4024) (tty-test)
2023-01-16T08:33:00.1911012Z Terminate orphan process: pid (1720) (conhost)
2023-01-16T08:33:00.1991583Z Terminate orphan process: pid (1088) (tty-test)
2023-01-16T08:33:00.2050288Z Terminate orphan process: pid (6148) (conhost)
2023-01-16T08:33:00.2109355Z Terminate orphan process: pid (6156) (tty-test)
2023-01-16T08:33:00.2168004Z Terminate orphan process: pid (6252) (conhost)
```

### Expected behavior

Explicitly terminate `tty-test` ? Normally we send SIGHUP when `:terminal` is closed, is that failing to kill children on Windows? 

Example test: https://github.com/neovim/neovim/blob/da267f3c2b8c5c688fc0f9f85e94ab35e670497d/test/functional/terminal/tui_spec.lua#L1356