Also needed to update some funcs that were taking a *testing.T to use a testing.TB. This prevents passing a nil pointer as a non-nil interface value
and thus making it impossible to detect nil before using the interfaces functions.
* Ensure the mesh gateway configuration comes back in the api within each upstream
* Add a test for the MeshGatewayConfig in the ToAPI functions
* Ensure we don’t use gateways for dc local connections
* Update the svc kind index for deletions
* Replace the proxycfg.state cache with an interface for testing
Also start implementing proxycfg state testing.
* Update the state tests to verify some gateway watches for upstream-targets of a discovery chain.