- most were trivial
- missing group close or open
- extra space
- no doxygen comment
- name commad might open an implicit group
this hould also be implicit cosed but does not happen somtimes
- crazy: internal declared groups have to be closed internal
When `xtimer_on_ztimer` is used, `xtimer` does not need to perform any clock
conversion. Especially undefined macros of `XTIMER_HZ` and `XTIMER_SHIFT` should
no longer result in compilation issues, as they are not used internally anyway.