[datadog_synthetics_global_variable] Remove drift on option argument

[ecdatadog]

When creating the resource

resource "datadog_synthetics_global_variable" "test_variable" {
  name        = "EXAMPLE_VARIABLE"
  description = "Description of the variable"
  tags        = ["foo:bar", "env:test"]
  value       = "variable-value"
}

the following drift was always present

Terraform will perform the following actions:

  # datadog_synthetics_global_variable.test_variable will be updated in-place
  ~ resource "datadog_synthetics_global_variable" "test_variable" {
        id               = "xxx"
        name             = "EXAMPLE_VARIABLE"
        tags             = [
            "foo:bar",
            "env:test",
        ]
        # (4 unchanged attributes hidden)

      - options {
          - totp_parameters {}
        }
    }

This PR removes this unwanted drift

[Drarig29]

LGTM, thank you!