message: add timeout support for Synapse notebook and job def
diff: "x-ms-discriminator-value": "SynapseNotebook",
  "allOf": [
  {
  - "$ref": "#/definitions/Activity"
  + "$ref": "#/definitions/ExecutionActivity"
  }
  ],
  "properties": {
  "x-ms-discriminator-value": "SparkJob",
  "allOf": [
  {
  - "$ref": "#/definitions/Activity"
  + "$ref": "#/definitions/ExecutionActivity"
  }
  ],
  "properties": {
  