(7.4.z) Remove expansion.pack.release.version and expansion.pack.release.name props from pom.xml

There are 2 environment variables (expansion.pack.release.version and expansion.pack.release.name in pom.xml which are left over from when the XP1 code was in the same source tree as base EAP. Now it is defined at https://github.com/jbossas/jboss-eap7/blob/xp-3.0.x/pom.xml#L87-L88.

No upstream required - WildFly code base does not include any expansion.pack properties.