Run TestSupervisorLogin only on valid HTTP/HTTPS supervisor addresses

We were assuming that env.SupervisorHTTPAddress was set, but it might not be
depending on the environment on which the integration tests are being run. For
example, in our acceptance environments, we don't currently set
env.SupervisorHTTPAddress.

I tried to follow the pattern from TestSupervisorOIDCDiscovery here.

Signed-off-by: Andrew Keesler <akeesler@vmware.com>

test/integration/supervisor_login_test.go

@@ -32,10 +32,26 @@ func TestSupervisorLogin(t *testing.T) {
 	ctx, cancel := context.WithTimeout(context.Background(), 5*time.Minute)
 	defer cancel()
 
+	tests := []struct {
+		Scheme   string
+		Address  string
+		CABundle string
+	}{
+		{Scheme: "http", Address: env.SupervisorHTTPAddress},
+		{Scheme: "https", Address: env.SupervisorHTTPSIngressAddress, CABundle: env.SupervisorHTTPSIngressCABundle},
+	}
+
+	for _, test := range tests {
+		scheme := test.Scheme
+		addr := test.Address
+		caBundle := test.CABundle
+
+		if addr == "" {
+			// Both cases are not required, so when one is empty skip it.
+			continue
+		}
+
 		// Create downstream OIDC provider (i.e., update supervisor with OIDC provider).
-	scheme := "http"
-	addr := env.SupervisorHTTPAddress
-	caBundle := ""
 		path := "/some/path"
 		issuer := fmt.Sprintf("https://%s%s", addr, path)
 		_, _ = requireCreatingOIDCProviderCausesDiscoveryEndpointsToAppear(
@@ -97,6 +113,7 @@ func TestSupervisorLogin(t *testing.T) {
 			rsp.Header.Get("Location"),
 		)
 	}
+}
 
 func makeDownstreamAuthURL(t *testing.T, scheme, addr, path string) string {
 	t.Helper()