core: Fix TestContext2Apply_cancel

Now that we populate a resource-level state pre-emptively for a resource,
before we apply the instances of that resource, it is no longer true that
this produces only one resource state, but the test below (comparing the
string version of the state) already captures the expected behavior and
so this additional check was redundant anyway.

terraform/context_apply_test.go

@@ -1906,11 +1906,6 @@ func TestContext2Apply_cancel(t *testing.T) {
 		t.Fatalf("unexpected errors: %s", applyDiags.Err())
 	}
 
-	mod := state.RootModule()
-	if len(mod.Resources) != 1 {
-		t.Fatalf("bad: %s", state.String())
-	}
-
 	actual := strings.TrimSpace(state.String())
 	expected := strings.TrimSpace(testTerraformApplyCancelStr)
 	if actual != expected {