Deprecates using exec workaround for ODL clustering

Deprecates using exec workaround for ODL clustering

Previously we had used an exec defined in puppet-tripleo to do
clustering with OpenDaylight docker containers.  The clustering issue is
now fixed in puppet-opendaylight by:
https://git.opendaylight.org/gerrit/#/c/60491

So removing the custom function and class workaround.  Also,
'ha_node_index' is deprecated for configuring clustering with
puppet-opendaylight so that is also removed.

Depends-On: I21c1eb2eff6d4cb855eff4a1122f55ad625d84cc

Change-Id: I7693b692c74071945fdcc08292542e9b458a540b
Signed-off-by: Tim Rozet <trozet@redhat.com>