CI fails on Windows

As discovered in [a CI run of](https://github.com/eclipse-cdt-cloud/cdt-gdb-adapter/actions/runs/17765008636/job/50486212913?pr=440) #440, some tests now fail on Windows. They still worked [last week](https://github.com/eclipse-cdt-cloud/cdt-gdb-adapter/actions/runs/17645432957/job/50142132911?pr=444).

The failing tests are:
* "after each" hook for _attach remote_ ▸ _can detach from a running program_, in all scenarios where it runs (defaults, remote, gdb-async-off, remote gdb-async-off).
* _launch_ ▸ _works with unicode in file names_, in all scenarios where it runs (defaults, gdb-async-off).

What I have found out so far:
* The difference is that [the OS image changed from Windows Server 2022 to Windows Server 2025](https://github.com/actions/runner-images/issues/12677).
* Apparently we are not using the GDB that is downloaded as part of the job, but one that is supplied with the OS image. That was version [11.2](https://github.com/eclipse-cdt-cloud/cdt-gdb-adapter/actions/runs/17645432957/job/50142132911?pr=444#step:4:498) before and [16.2](https://github.com/eclipse-cdt-cloud/cdt-gdb-adapter/actions/runs/17765008636/job/50486212913?pr=440#step:4:494) now.
* We could work around the CI failures by reverting to the `Windows-2022` image, but if there are actual problems with GDB 16, we should probably fix them anyway.
* I can reproduce the problem that GDB 16.2 becomes unresponsive when the `gdbserver` that it is attached to is killed while the program is running, after outputting `warning: Exception condition detected on fd`.