core: Fix TestContext2Apply_multiProviderDestroyChild

We now correctly prune out empty modules after destroying everything
inside them, so we need to update this expectation string to match the new
behavior, rather than before when it was actually describing a buggy
result.

terraform/context_apply_test.go

@@ -3436,8 +3436,6 @@ func TestContext2Apply_multiProviderDestroyChild(t *testing.T) {
 
 	checkStateString(t, state, `
 <no state>
-module.child:
-  <no state>
 `)
 }