[network][2021-08-01], wrong api-version for vmssNetworkInterface and vmssNetworkPublicIpAddress

In `2021-08-01`, `vmssNetworkInterface` and `vmssNetworkPublicIpAddress` in Network has api-version `2021-08-01`

https://github.com/Azure/azure-rest-api-specs/blob/b71da9841769cfdf17c43d3dc58195f1237f1bed/specification/network/resource-manager/Microsoft.Network/stable/2021-08-01/vmssNetworkInterface.json#L6

https://github.com/Azure/azure-rest-api-specs/blob/b71da9841769cfdf17c43d3dc58195f1237f1bed/specification/network/resource-manager/Microsoft.Network/stable/2021-08-01/vmssPublicIpAddress.json#L6

Hence generated SDK would uses 2021-08-01 in these APIs, which is not deployed in backend. Attempt to call using this version will result in exception from backend:
>The supported api-versions are '2015-05-01-preview, 2015-06-15, 2016-03-30, 2016-04-30-preview, 2016-06-01, 2016-07-01, 2016-08-01, 2016-09-01, 2017-03-30, 2017-12-01, 2018-04-01, 2018-06-01, 2018-10-01, 2019-03-01, 2019-07-01, 2019-12-01, 2020-06-01, 2020-12-01, 2021-03-01, 2021-04-01, 2021-07-01, 2021-11-01, 2022-03-01'. The supported locations are 'eastus, eastus2, westus, centralus, northcentralus, southcentralus, northeurope, westeurope, eastasia, southeastasia, japaneast, japanwest, australiaeast, australiasoutheast, australiacentral, brazilsouth, southindia, centralindia, westindia, canadacentral, canadaeast, westus2, westcentralus, uksouth, ukwest, koreacentral, koreasouth, francecentral, southafricanorth, uaenorth, switzerlandnorth, germanywestcentral, norwayeast, jioindiawest, westus3, swedencentral, eastus2euap, centraluseuap'

@MikhailTryakhov Please take a look at these two swagger files.

PS: Currently, java SDK added a directive to change back the version to previous one(2018-10-01) as a workaround. We'll delete the directive once a supported version is chosen for these swagger files.

Inspect the two linked specification files, specification/network/resource-manager/Microsoft.Network/stable/2021-08-01/vmssNetworkInterface.json and vmssPublicIpAddress.json, especially their API-version declarations. Compare them with the backend-supported versions listed in the issue and check the generated SDK behavior. Done means both swagger files use a deployed version so these APIs no longer request 2021-08-01.

Written by the indexing model from the issue text.