test(e2e): do not require kubetest configration if not needed

Even if conformance tests are skipped, the kubetest configuration is still required and expected to exist

Author: vknabel

test/e2e/cluster_upgrade.go

@@ -112,9 +112,11 @@ func ClusterUpgradeConformanceSpec(ctx context.Context, inputGetter func() Clust
 		Expect(input.E2EConfig.Variables).To(HaveKey(KubernetesVersionUpgradeFrom))
 		Expect(input.E2EConfig.Variables).To(HaveKey(KubernetesVersionUpgradeTo))
 
-		Expect(input.E2EConfig.Variables).To(HaveKey(kubetestConfigurationVariable), "% spec requires a %s variable to be defined in the config file", specName, kubetestConfigurationVariable)
-		kubetestConfigFilePath = input.E2EConfig.MustGetVariable(kubetestConfigurationVariable)
-		Expect(kubetestConfigFilePath).To(BeAnExistingFile(), "%s should be a valid kubetest config file")
+		if !input.SkipConformanceTests {
+			Expect(input.E2EConfig.Variables).To(HaveKey(kubetestConfigurationVariable), "% spec requires a %s variable to be defined in the config file", specName, kubetestConfigurationVariable)
+			kubetestConfigFilePath = input.E2EConfig.MustGetVariable(kubetestConfigurationVariable)
+			Expect(kubetestConfigFilePath).To(BeAnExistingFile(), "%s should be a valid kubetest config file")
+		}
 
 		if input.ControlPlaneMachineCount == nil {
 			controlPlaneMachineCount = 1