Adapt e2e tests to Inventory 0.1.0

Citing from rhn-engineering-lkrejci 's mail

Following the suite of metrics, inventory will no longer support the tenantID
in the URL and will solely rely on Hawkular accounts to hand it the tenantID
to use - i.e. it will be the tenant of the currently logged in user or of the
persona passed in using the "Hawkular-Persona" header.