Handle inherited associations same as direct

[alesz]

Issue type

[ ] Feature request
[x] Bug report
[ ] Documentation

Environment

• Python version: 3.6
• NetBox version: 2.3.4

Description

Steps to reproduce:

1. Add tenant A
2. Add vrf B and associate it with tenant A
3. Add prefix C and associate it with vrf B. Don't associate with tenant A.

Observed:

Displaying prefix C shows Tenant A with Inherited tag. Displaying tenant A counts prefix C in stats. Prefix is associated with tenant via vrf object (inherited tag) if tenant field is not set.
Clicking on prefixes in tenant A stats opens /ipam/prefixes/?tenant=A.

Error:

List of prefixes is empty, tenant search filter shows A(0). Setting tenant to -- None -- displays prefix correctly.

Expected:

prefix behaves in same way with inherited tenant as with associated one.

[jeremystretch]

I think this highlights how fragile the concept of inherited tenancy is, not to mention that it's completely absent in the REST API. I think we're better off just ditching it.