Converting survey JSON from V1 to V2 incorrectly changes `"showNavigationButtons": "both"` to `"showNavigationButtons": false`

[JaneSjs]

T25205 - Possible regression in handling showNavigationButtons: "both" after upgrade to v2.2.3 (React)
https://surveyjs.answerdesk.io/internal/ticket/details/T25205

---

An example of a survey JSON definition in v1: View Demo.

 {
  pages: [
    {
      name: "page1",
      title: "Page 1",
      elements: [
        {
          type: "radiogroup",
          name: "question1",
          choices: ["Item 1", "Item 2", "Item 3"],
        },
        {
          type: "boolean",
          name: "question2",
        },
      ],
    },
    {
      name: "page3",
      title: "Page 2",
      elements: [
        {
          type: "radiogroup",
          name: "question4",
          choices: ["Item 1", "Item 2", "Item 3"],
        },
        {
          type: "boolean",
          name: "question5",
        },
      ],
    },
    {
      name: "page2",
      title: "Page 3",
      elements: [
        {
          type: "text",
          name: "question3",
        },
      ],
    },
  ],
  showNavigationButtons: "both",
}

When this survey is loaded within SurveyJS Creator v2, the showNavigationButtons property value is converted to false.
Try loading this JSON at https://surveyjs.io/create-free-survey. You'll get the following output:

{
  "pages": [
    {
      "name": "page1",
      "title": "Page 1",
      "elements": [
        {
          "type": "radiogroup",
          "name": "question1",
          "choices": [
            "Item 1",
            "Item 2",
            "Item 3"
          ]
        },
        {
          "type": "boolean",
          "name": "question2"
        }
      ]
    },
    {
      "name": "page3",
      "title": "Page 2",
      "elements": [
        {
          "type": "radiogroup",
          "name": "question4",
          "choices": [
            "Item 1",
            "Item 2",
            "Item 3"
          ]
        },
        {
          "type": "boolean",
          "name": "question5"
        }
      ]
    },
    {
      "name": "page2",
      "title": "Page 3",
      "elements": [
        {
          "type": "text",
          "name": "question3"
        }
      ]
    }
  ],
  "showNavigationButtons": false
}

Expected behavior: the showNavigationButtons: "both" property is converted to "navigationButtonsLocation": "topBottom".

{
  "pages": [
    {
      "name": "page1",
      "title": "Page 1",
      "elements": [
        {
          "type": "radiogroup",
          "name": "question1",
          "choices": [
            "Item 1",
            "Item 2",
            "Item 3"
          ]
        },
        {
          "type": "boolean",
          "name": "question2"
        }
      ]
    },
    {
      "name": "page3",
      "title": "Page 2",
      "elements": [
        {
          "type": "radiogroup",
          "name": "question4",
          "choices": [
            "Item 1",
            "Item 2",
            "Item 3"
          ]
        },
        {
          "type": "boolean",
          "name": "question5"
        }
      ]
    },
    {
      "name": "page2",
      "title": "Page 3",
      "elements": [
        {
          "type": "text",
          "name": "question3"
        }
      ]
    }
  ],
  "navigationButtonsLocation": "topBottom"
}