EmailTask breaking change

[hyzx86]

The PR #13426 will cause some problems,

I had a workflow that I created 2 years ago, and I wasn't sure which field would be the body of the email, so I wrote it in both places

The Settings below used to use 'Body' as the body of the email. After updating the OC version, it found that it used 'BodyText' as the body

            {
              "ActivityId": "472xt4dht0zxq2p4hqc5f8a850",
              "Name": "EmailTask",
              "X": 950,
              "Y": 1300,
              "IsStart": false,
              "Properties": {
                "Sender": {
                  "Expression": null
                },
                "Author": {
                  "Expression": null
                },
                "Recipients": {
                  "Expression": "{{Workflow.Properties[\"cUser\"].Email}}"
                },
                "Subject": {
                  "Expression": "TMS DN Post Result"
                },
                "Body": {
                  "Expression": "<style>...............\r\n  </div>\r\n  "
                },
                "IsBodyHtml": true,
                "BodyText": {
                  "Expression": "11111111111"
                },
                "IsBodyText": false,
                "Cc": {
                  "Expression": null
                },
                "ActivityMetadata": {
                  "Title": "TMS DN Post Result"
                },
                "IsHtmlBody": true
              }
            }

[hyzx86]

@hishamco

The unit tests is using 'Body' Field