NETVIRT-1262: Tep's are not part of transport zone when a transport zone

NETVIRT-1262: Tep's are not part of transport zone when a transport zone
is removed and added from NB

Problem
-------
TEPs do not add back to transport-zone which is removed and then added
again from northbound.

Problem solution
----------------
When tz delete event arrives for a particular Transport zone,
teps of that will be moved to tepsInNotHostedTransportZone OperDs.
And, when same name tz gets re-added from NBI, then these teps
will go back to re-added tz.

Change-Id: I482528a1e695ee439ca731c63138639dff2dce3f
Signed-off-by: Nishchya Gupta <nishchyag@altencalsoftlabs.com>