Allow disabling network security stage

[juliocc]

This PR:

• Removes some incorrect bindings that were failing when the security stage is disabled.
• Some potential errors being masked by try()s.
• Binding to an non-existing network_firewall_policies_viewer custom role.

[juliocc]

The test failure is expected. We where previously assigning the network_firewall_policies_admin role always, but it's only needed if network_security is enabled.

So we either extend the test to enable network_security or we keep it as is and just remove that binding from the inventory.

[ludoo]

see comments, nsec != security

[ludoo]

thanks for being patient lol