Reduce the cost of initializing a blobstore connection

When getting the fog directory that represents the blobstore resource
bucket, try to limit the provider's entries per page return to 1 as
our use cases do not require the bucket entries to be retrieved.

This change improved the time required to connect to a swift store with
25 thousand entries in the bucket from over 2 seconds to under 100ms.

[#74825494]

Signed-off-by: Michael Fraenkel <fraenkel@us.ibm.com>