Microsoft.Web GET geoRegions response only has 3 regions starting in 2020-12-01

Starting in version `2020-12-01`, [GET Microsoft.Web/geoRegions](https://docs.microsoft.com/en-us/rest/api/appservice/list-geo-regions/list-geo-regions) is returning a greatly reduced list of regions compared to older API versions (`2020-10-01` and older).

Expected:
Response includes 37 regions.
`GET https://management.azure.com/subscriptions/{subscriptionId}/providers/Microsoft.Web/geoRegions?api-version=2020-10-01
`
```json
{
"value": [
{
"id": "/subscriptions/{subscriptionId}/providers/Microsoft.Web/geoRegions/Central US",
"name": "Central US",
"type": "Microsoft.Web/geoRegions",
"properties": {
"name": "Central US",
"description": null,
"sortOrder": 0,
"displayName": "Central US",
"orgDomain": "PUBLIC;DREAMSPARK;MSFTPUBLIC;FUNCTIONS;DYNAMIC;DSERIES;LINUX;LINUXDSERIES;ELASTICPREMIUM;LINUXFREE;LINUXDYNAMIC;ELASTICLINUX;XENON;XENONV3;WINDOWSV3;LINUXV3"
}
},
{
"id": "/subscriptions/{subscriptionId}/providers/Microsoft.Web/geoRegions/North Europe",
"name": "North Europe",
"type": "Microsoft.Web/geoRegions",
"properties": {
"name": "North Europe",
"description": null,
"sortOrder": 1,
"displayName": "North Europe",
"orgDomain": "PUBLIC;DREAMSPARK;MSFTPUBLIC;FUNCTIONS;DYNAMIC;DSERIES;LINUX;LINUXDSERIES;XENON;ELASTICPREMIUM;LINUXFREE;ELASTICLINUX;LINUXDYNAMIC;XENON;XENONV3;WINDOWSV3;LINUXV3"
}
},
... truncated for brevity
{
"id": "/subscriptions/{subscriptionId}/providers/Microsoft.Web/geoRegions/Korea Central",
"name": "Korea Central",
"type": "Microsoft.Web/geoRegions",
"properties": {
"name": "Korea Central",
"description": null,
"sortOrder": 2147483647,
"displayName": "Korea Central",
"orgDomain": "PUBLIC;DREAMSPARK;MSFTPUBLIC;FUNCTIONS;DYNAMIC;LINUX;LINUXDSERIES;ELASTICPREMIUM;LINUXFREE;DSERIES;LINUXDYNAMIC;ELASTICLINUX;XENON;XENONV3;WINDOWSV3;LINUXV3"
}
}
],
"nextLink": null,
"id": null
}
```

Actual:
Response includes 3 regions.
`GET https://management.azure.com/subscriptions/{subscriptionId}/providers/Microsoft.Web/geoRegions?api-version=2020-12-01`
```json
{
"value": [
{
"id": "/subscriptions/{subscriptionId}/providers/Microsoft.Web/geoRegions/South Central US",
"name": "South Central US",
"type": "Microsoft.Web/geoRegions",
"properties": {
"name": "South Central US",
"description": null,
"sortOrder": 11,
"displayName": "South Central US",
"orgDomain": "PUBLIC;DREAMSPARK;MSFTPUBLIC;FUNCTIONS;DYNAMIC;DSERIES;LINUX;LINUXDSERIES;ELASTICPREMIUM;LINUXFREE;LINUXDYNAMIC;ELASTICLINUX;XENON;XENONV3;WINDOWSV3;LINUXV3"
}
},
{
"id": "/subscriptions/{subscriptionId}/providers/Microsoft.Web/geoRegions/South Africa North",
"name": "South Africa North",
"type": "Microsoft.Web/geoRegions",
"properties": {
"name": "South Africa North",
"description": null,
"sortOrder": 2147483647,
"displayName": "South Africa North",
"orgDomain": "PUBLIC;MSFTPUBLIC;FUNCTIONS;DYNAMIC;LINUX;LINUXDSERIES;DSERIES;ELASTICPREMIUM;ELASTICLINUX;XENON;XENONV3;WINDOWSV3;LINUXV3"
}
},
{
"id": "/subscriptions/{subscriptionId}/providers/Microsoft.Web/geoRegions/South Africa West",
"name": "South Africa West",
"type": "Microsoft.Web/geoRegions",
"properties": {
"name": "South Africa West",
"description": null,
"sortOrder": 2147483647,
"displayName": "South Africa West",
"orgDomain": "PUBLIC;LINUX;LINUXDSERIES;DSERIES"
}
}
],
"nextLink": null,
"id": null
}
```

Start by comparing the Microsoft.Web/geoRegions responses for API versions 2020-10-01 and 2020-12-01 at the management.azure.com endpoints shown in the issue. Confirm the service behavior and locate the corresponding Microsoft.Web API specification; done means the repository specification accurately reflects the confirmed API contract or documents why no specification change is appropriate.

Written by the indexing model from the issue text.