[SYM-3790] Followup: fix sym_flow resource acceptance test

[Arianna2028]

Last 2 PRs had some conflicting changes that broke a test so this fixes that.

[linear]

SYM-3790 Support Flows without scheduled de-escalation

For context, see the AaaS ADR.

Add an optional schedule_deescalation boolean (default true) to the params of a sym_flow resource that, when false, suppresses scheduling of the deescalate event. This should be at the params level alongside the existing allow_revoke.

This will require Terraform provider (specifically, /sym/templates/sym_approval.go) and platform changes.

Also add queuer API-level validations that if schedule_deescalation is false, then allow_revoke must be true and duration must not be specified in the prompt_fields (but Flows may still have a duration; we will just ignore it—we'll make this better in SYM-3791).

Example Terraform:

resource "sym_flow" "custom" {
  # ...
  params = {
    strategy_id           = sym_strategy.custom[0].id
    schedule_deescalation = false
    allow_revoke          = true
    prompt_fields_json    = jsonencode([
      {
        name     = "identifier"
        label    = "What animal would you like?"
        type     = "string"
        required = true
      }
    ])
  }
}