Bug: the azure-devops cache folder location is computed differently in different places

The Azure DevOps CLI has a way to redirect the config and the cache directory to a different location.

In most code paths it's enough to only redirect the CONFIG directory and in that case the cache folder will automatically be placed underneath the config folder.

But there are a few places in which the cache folder is placed under the home directory instead.

Under home
https://github.com/Azure/azure-devops-cli-extension/blob/bd34a6fd0658a15dadf6c09c7f6217ca5ffa662b/azure-devops/azext_devops/devops_sdk/_file_cache.py#L114

Under config
https://github.com/Azure/azure-devops-cli-extension/blob/bd34a6fd0658a15dadf6c09c7f6217ca5ffa662b/azure-devops/azext_devops/dev/common/file_cache.py#L15

I'd expect a single consistent behavior.

https://github.com/search?q=repo%3AAzure%2Fazure-devops-cli-extension+os.getenv&type=code