Neutron FWaaS firewall object does not support 'shared' attribute
at now and 'shared' attribute is not included in API response.
This commmit removes 'shared' attribute for firewall object.
For more detail of the background, please see the bug report.
Note that 'shared' attributes for firewall rule and policy
are supported. This commit only affect the firewall object.
Change-Id: I5787529395e0005ce1efee48beb6f0f688c1c736
Closes-Bug: #1465440
991d8ac86c