Plotting of rate vectors is wrong

[sondreso]

What happened? (You can include a screenshot if it helps explain)

Rate vectors are special in reservoir simulators, in that every data-point is valid backwards in time (but not including) the current time-step. See: https://equinor.github.io/fmu-ensemble/usage.html#rate-handling-in-eclipse-summary-vectors

Rate vectors are currently plotted with linear interpolation between the report steps.

See also: #8572

What did you expect to happen?

We should plot it with steps (using pre) instead:

From: https://matplotlib.org/stable/gallery/lines_bars_and_markers/step_demo.html

steps to reproduce

TBD

See internal discussions here

Environment where bug has been observed

• python 3.8
• python 3.9
• python 3.10
• python 3.11
• python 3.12
• macosx
• rhel7
• rhel8
• local queue
• lsf queue
• slurm queue
• openPBS queue
• used flag --enable-scheduler