When connect is disabled the discovery-chain endpoint returns a 500
error status, which we previoulsy did not gracefully cope with.
This commit gracefully copes with any errors from the disco-chain
endpoint by supressing the error and hiding the Routing tab from the
Service detail page.
Acceptance test included
* Adds conditional in route to not make discovery-chain request if service kind is equal to `connect-proxy` or `mesh-gateway`
* Adds conditional in template to not show Routing tab if `chain` returns as null
* Creates a new acceptance test to test the Routing tab not being displayed for a service proxy
* Adds `tabs` to the services/show page object