The documentation seems to suggest that I can specify which functions should start by specifying the functions of interest to run in my local.settings.json

I tried defining at the top level

{
  ...
  "functions": ["RunJustThisFunction"]
  ...
}

and at the Values level.

{
  ...
  "Values": {
    ...
    "functions": ["RunJustThisFunction"]
    ...
  }
  ...
}

But when I run the app I see all of the functions trying to execute.