CA-255547: WLB code in XenCenter: Remove all code targetting <= 6.1 XenServers
CA-255547: WLB code in XenCenter: Remove all code targetting <= 6.1 XenServers

Fixed build by removing unused fields that caused the Release build to fail. Removed more dead code.

Signed-off-by: Gabor Apati-Nagy <fea1aad7ceb67d3aeb88acb6b51e51467c21418e@citrix.com>

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