The OS default firewall section doesn't have tags. To be consistent
with other resources created from our plugin, adding tags on
this firewall section. Moreover, the cleanup util will clean up
backend resources created by our plugin based on the tags. If the
resource doesn't have tag, cleanup util cannot clean it up.
Also changing the shared tenant-id to use predefined string in
nsx_constants for dhcp and port switching profile.
Closes-bug: #1519091
Change-Id: Ib6db65b36030e863e1630c118910c168e9ab1a13
ffaf285425