kube-proxy: drop iptables version check

Kube-proxy's iptables mode used to care whether utiliptables's
EnsureRule was able to use "iptables -C" or if it had to implement it
hackily using "iptables-save". But that became irrelevant when
kube-proxy was reimplemented using "iptables-restore", and no one ever
noticed. So remove that check.

cmd/kube-proxy/app/server_test.go

@@ -38,53 +38,6 @@ import (
 	utilpointer "k8s.io/utils/pointer"
 )
 
-type fakeIPTablesVersioner struct {
-	version string // what to return
-	err     error  // what to return
-}
-
-func (fake *fakeIPTablesVersioner) GetVersion() (string, error) {
-	return fake.version, fake.err
-}
-
-func (fake *fakeIPTablesVersioner) IsCompatible() error {
-	return fake.err
-}
-
-type fakeIPSetVersioner struct {
-	version string // what to return
-	err     error  // what to return
-}
-
-func (fake *fakeIPSetVersioner) GetVersion() (string, error) {
-	return fake.version, fake.err
-}
-
-type fakeKernelCompatTester struct {
-	ok bool
-}
-
-func (fake *fakeKernelCompatTester) IsCompatible() error {
-	if !fake.ok {
-		return fmt.Errorf("error")
-	}
-	return nil
-}
-
-// fakeKernelHandler implements KernelHandler.
-type fakeKernelHandler struct {
-	modules       []string
-	kernelVersion string
-}
-
-func (fake *fakeKernelHandler) GetModules() ([]string, error) {
-	return fake.modules, nil
-}
-
-func (fake *fakeKernelHandler) GetKernelVersion() (string, error) {
-	return fake.kernelVersion, nil
-}
-
 // This test verifies that NewProxyServer does not crash when CleanupAndExit is true.
 func TestProxyServerWithCleanupAndExit(t *testing.T) {
 	// Each bind address below is a separate test case