core: rm unneeded disconnect when reconstructing

When performing reconstruct in the case that the old master status
isn't changed to inactive there is a call to disconnect from it.
This operation is wrong, there is no need to disconnect from the
current master which can only cause issues.

Change-Id: Ic3a0a3014d19ae78ddb47ef1a8ad4aa950539a9c
Related-To: https://bugzilla.redhat.com/show_bug.cgi?id=1016118
Signed-off-by: Liron Aravot <laravot@redhat.com>