AWS Template S3 bucket prefixes might not match defaults in `metaflow configure aws`

[dennismoe]

I encountered a small issue.
The default S3 prefixes in the AWS Template might not match with the suggested S3 prefixes in metaflow configure aws

https://github.com/outerbounds/metaflow-tools/blob/b76986369a8a44ce6186743c95c7e65143335982/aws/cloudformation/metaflow-cfn-template.yml#L1835-L1840

  MetaflowDataStoreS3Url:
    Description: Amazon S3 URL for Metaflow DataStore [METAFLOW_DATASTORE_SYSROOT_S3]
    Value: !Sub "s3://${MetaflowS3Bucket}/metaflow"
  MetaflowDataToolsS3Url:
    Description: Amazon S3 URL for Metaflow DataTools [METAFLOW_DATATOOLS_S3ROOT]
    Value: !Sub "s3://${MetaflowS3Bucket}/data"

metaflow configure aws suggests metaflow/data as default prefix for METAFLOW_DATATOOLS_S3ROOT if the environment variable METAFLOW_DATATOOLS_S3ROOT isn't set already - what should not be assumed in my opinion.

metaflow/metaflow/cmd/configure_cmd.py

Lines 262 to 265 in 01e52c5

	default=existing_env.get(
	"METAFLOW_DATATOOLS_S3ROOT",
	os.path.join(env["METAFLOW_DATASTORE_SYSROOT_S3"], "data"),
	),