Adding a parameter to fix the scale max value of graphs

[Frix-x]

Describe the feature or hardware support you'd like

Add a macro parameter like MAX_SCALE=XXX to specify and force the scaling of the energy graphs.
If the variable is unset, it will stay at "auto" as it's today.

This will allow better comparison of several consecutive runs by forcing Xe7 or Xe8 as the max scale value for all of them.

Additional context or information

No response