Update storage configuration samples

[chlowell]

Samples currently show configuring clients with internal APIs. For example, this one imports create_configuration from _shared and uses an underscored keyword argument:

azure-sdk-for-python/sdk/storage/azure-storage-blob/samples/blob_samples_proxy_configuration.py

Lines 47 to 55 in 39c3c40

	# Create a storage Configuration object and update the proxy policy.
	config = create_configuration(storage_sdk='blob')
	config.proxy_policy.proxies = {
	'http': http_proxy,
	'https': https_proxy
	}
	# Construct the BlobServiceClient, including the customized configuation.
	service_client = BlobServiceClient.from_connection_string(connection_string, _configuration=config)
	containers = list(service_client.list_containers(logging_enable=True))

[xiangyan99]

#21762

[tasherif-msft]

Resolved