Improve functions like show_subsystems_tree_call() on string manipulation

[qdeslandes]

Is your feature request related to a problem? Please describe.

Functions manipulating strings like show_subsystems_tree_call() tends to be messy, especially when using strncpy().

Describe the solution you'd like

Rewrite such function using pointer arithmetic.

Describe alternatives you've considered

N/A

Additional context

N/A