INTEG-330 [integ-forum] Rendering error of Forum activity after renaming a space

Fix description: in function buildSpaceLink of BuildLinkUtils class, use method getSpaceHomeURL from social to get new space url.
INTEG-330 [integ-forum] Rendering error of Forum activity after renaming a space

Fix description:
- use ForumActivityUtils.getSpaceService() to get SpaceService
- delete method getSpaceHomeURL(String spaceGroupId) because we don't need it anymore