[BUG] [ResourceHealth] Property refreshTimestamp returned by the service does not follow the RFC format

### API Spec link

https://github.com/Azure/azure-rest-api-specs/blob/main/specification/resourcehealth/resource-manager/Microsoft.ResourceHealth/stable/2022-10-01/ResourceHealth.json#L2121C10-L2121C26

### API Spec version

2022-10-01

### Describe the bug

The API https://learn.microsoft.com/en-us/rest/api/resourcehealth/emerging-issues/list?view=rest-resourcehealth-2022-10-01&tabs=HTTP returns property `refreshTimestamp` with value in format like `2024-10-30 06:54:11Z`. Yet according to https://datatracker.ietf.org/doc/html/rfc3339#section-5.8, a vaild date-time string should be like `2024-10-30T06:54:11Z`.

### Expected behavior

Return date-time string in format like `2024-10-30T06:54:11Z`.

### Actual behavior

It returns `2024-10-30 06:54:11Z` that is not a valid date-time string and has caused deserialization error in SDK.

### Reproduction Steps

Calling API https://learn.microsoft.com/en-us/rest/api/resourcehealth/emerging-issues/list?view=rest-resourcehealth-2022-10-01&tabs=HTTP.

### Environment

_No response_

Start with the ResourceHealth.json definition at the linked line for refreshTimestamp and compare its declared date-time format with the reported service response and RFC3339. Check whether the correction belongs in this API specification or requires a service-side fix; done means the response and SDK deserialization conform to the expected RFC3339 format.

Written by the indexing model from the issue text.