fix(cat-gateway): Fix health endpoints response schema and status code

[bkioshn]

Description

DO NOT MERGE THIS PR, SINCE STATUS CODE ISSUE IS NOT RESOLVED

• Fix response violates schema error happen in schemathesis

Related Issue(s)

Closes #1501

Description of Changes

Since the fields in ContentErrorDetail can be None, add nullable

Schema

Schema before

"ContentErrorDetail": {
        "type": "object",
        "description": "Individual details of a single error that was detected with the content of the\nrequest.",
        "properties": {
          "loc": {
            "type": "array",
            "description": "The location of the error",
            "items": {
              "type": "string",
              "format": "error",
              "title": "Error Message",
              "description": "This is an error message.",
              "example": "An error has occurred, the details of the error are ...",
              "maxLength": 256,
              "minLength": 1,
              "pattern": "^(.){1,256}$"
            },
            "maxItems": 100
          },
          "msg": {
            "type": "string",
            "format": "error",
            "title": "Error Message",
            "description": "The error message.",
            "example": "An error has occurred, the details of the error are ...",
            "maxLength": 1000,
            "minLength": 1,
            "pattern": "^[0-9a-zA-Z].*$"
          },
          "type": {
            "type": "string",
            "format": "error",
            "title": "Error Message",
            "description": "The type of error",
            "example": "An error has occurred, the details of the error are ...",
            "maxLength": 1000,
            "minLength": 1,
            "pattern": "^[0-9a-zA-Z].*$"
          }
        },
        "example": {
          "loc": [
            "body"
          ],
          "msg": "Value is not a valid dict.",
          "type": "type_error.dict"
        }
      },

After

 "ContentErrorDetail": {
        "type": "object",
        "description": "Individual details of a single error that was detected with the content of the\nrequest.",
        "properties": {
          "loc": {
            "type": "array",
            "description": "The location of the error",
            "items": {
              "type": "string",
              "format": "error",
              "title": "Error Message",
              "description": "This is an error message.",
              "example": "An error has occurred, the details of the error are ...",
              "maxLength": 256,
              "minLength": 1,
              "pattern": "^(.){1,256}$"
            },
            "nullable": true,
            "maxItems": 100
          },
          "msg": {
            "type": "string",
            "format": "error",
            "title": "Error Message",
            "description": "The error message.",
            "nullable": true,
            "example": "An error has occurred, the details of the error are ...",
            "maxLength": 1000,
            "minLength": 1,
            "pattern": "^[0-9a-zA-Z].*$"
          },
          "type": {
            "type": "string",
            "format": "error",
            "title": "Error Message",
            "description": "The type of error",
            "nullable": true,
            "example": "An error has occurred, the details of the error are ...",
            "maxLength": 1000,
            "minLength": 1,
            "pattern": "^[0-9a-zA-Z].*$"
          }
        },
        "example": {
          "loc": [
            "body"
          ],
          "msg": "Value is not a valid dict.",
          "type": "type_error.dict"
        }
      },

Please confirm the following checks

• My code follows the style guidelines of this project
• I have performed a self-review of my code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes
• Any dependent changes have been merged and published in downstream module

[github-actions]

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[github-actions]

❌ Test Report | ${\color{lightgreen}Pass: 389/392}$ | ${\color{red}Fail: 3/392}$ |

[github-actions]

❌ Test Report | ${\color{lightgreen}Pass: 389/392}$ | ${\color{red}Fail: 3/392}$ |

[github-actions]

❌ Test Report | ${\color{lightgreen}Pass: 409/412}$ | ${\color{red}Fail: 3/412}$ |

[github-actions]

❌ Test Report | ${\color{lightgreen}Pass: 442/445}$ | ${\color{red}Fail: 3/445}$ |

[github-actions]

❌ Test Report | ${\color{lightgreen}Pass: 442/445}$ | ${\color{red}Fail: 3/445}$ |