Remove partial export of javassist from weld osgi bundle

The current weld osgi bundle exports javassist.util.proxy. This was earlier done in Weld 1.0 for handling references to util.proxy classes during proxy class loading in the context of an application classloader. With the new proxy SPI changes, it is possible for a Weld SPI implementation to provide a classloader to handle Proxy class loading. This make the current export of javassist.util.proxy unnecessary and also has been known to cause other issues [see GlassFish issue 12368 and WELD-570]