LPS-30322 Undo some source formtting for performance and threadsafty purposes

Hey Brian,

Those finals are required for threadsafty.
SPIConfiguration.fromXMLString() needs to call Long.parseLong() in order to throw out NumberFormatException on bad xml content, it can not silently convert bad setting to default 0.
SPIKey is private class, not possible to be used outside of MPIHelperUtil, no need to do the instanceof checking. Calculating hashcode bases toString() is no good, it forces us to create the temp toString() objects.