Unbreak compile with Unix Makefile and newer CMake

Disable AUTOMOC for the "path with space" folder, which isn't
needed here anyways. This unbreaks the Unix Makefile cmake generator
in recent versions, to fix the CI issue:

```
make[2]: *** No rule to make target 'plugins/debuggercommon/tests/debuggees/path\ with\ space/CMakeFiles/debuggee_spacedebugee_autogen.dir/compiler_depend.ts',
needed by 'plugins/debuggercommon/tests/debuggees/path with space/debuggee_spacedebugee_autogen/timestamp'.  Stop.
```

See also: https://gitlab.kitware.com/cmake/cmake/-/issues/25554

(cherry picked from commit b1c227f0)