Fix Astyanax config regression

c209160ecacc5498475d98b717c29f1ba7ac1439 forced Astyanax's
NodeDiscoveryType and ConnectionPoolType settings to their respective
Astyanax-level defaults (not the defaults at the top of
AstyanaxStorageManager.java).  At issue was a builder method called
twice without coordination between the two calls.

This commit also removes the superfluous "storage" prefix on config
keys used in InternalAstyanaxKCVTest.