test: move creation of Istio resources into `It`
test: move creation of Istio resources into `It`

The creation of Istio resources in the Istio CI test contains assertions.
Previously, these were ran in the `BeforeAll` block. If the assertions failed,
`AfterFailed` would not be invoked (which is most likely a bug). To ensure that
we are able to debug the Istio test, for now, move the creation of Istio
resources / the assertions on their readiness and corectness into the `It` for
the Istio test. No other `It`s are used in this test, so no other test
functionality is broken here. In the future, this commit can be reverted when
`AfterFailed` is invoked when assertions fail in `BeforeAll`.

Signed-off by: Ian Vernon <ian@cilium.io>

cilium/cilium,cilium-team/cilium,tklauser/cilium,michi-covalent/cilium,michi-covalent/cilium,tgraf/cilium,tklauser/cilium,cilium/cilium,cilium-team/cilium,michi-covalent/cilium,tklauser/cilium,tgraf/cilium,cilium/cilium,tgraf/cilium,michi-covalent/cilium,michi-covalent/cilium,cilium/cilium,tgraf/cilium,cilium/cilium,tgraf/cilium,tklauser/cilium,tgraf/cilium,tklauser/cilium