This is a follow-up to https://git.opendaylight.org/gerrit/#/c/31448/ to
make LocalThreePhaseCommitCohort::operationError final and remove the
setter. The callers were refactored to use the
LocalThreePhaseCommitCohort ctor that passes the operationError.
Change-Id: I68f69be08e7f74524e92f224172ebf1ca9469017
Signed-off-by: Tom Pantelis <tpanteli@brocade.com>