Exclude example email template from workflows

[bjarnef]

Now that default themes, export and email templates are served via static assets, there doesn't seem to be a way to exclude default example email template, which may not be relevant to use, when custom email templates are added.

[AndyButland]

We'll add a configuration option for this for the next release for Forms 10:

    "Forms": {
      "FormDesign": {
        "RemoveProvidedEmailTemplate": true
      },
    }