Combine PB/Invocable and Developer mode into 1 option

[mkolodner]

Is your feature request related to a problem? Please describe.
A feature request, not related to a problem.

Describe the solution you'd like
When we rename calculation modes (currently planned, with the names in discussion) we believe we can collapse "Developer" and "Process Builder." And we believe that in the code Process Builder actually doesn't have any effect, so these should be collapsed, extraneous code removed, and all those set to "Process Builder" should be set to "Developer" (even though that won't be what people see in the UI, because we're planning to rename that to "Invocable by Automation."

Describe alternatives you've considered
N/A

Additional context
Issue created during Chicago Sprint October 2023 after discussion of the renaming options for Calculation Mode and the other buttons.