Remove support for basic authentication

This change removes support for basic authn in v1.19 via the
--basic-auth-file flag.  This functionality was deprecated in v1.16
in response to ATR-K8S-002: Non-constant time password comparison.

Similar functionality is available via the --token-auth-file flag
for development purposes.

Signed-off-by: Monis Khan <mok@vmware.com>

pkg/kubeapiserver/options/authentication_test.go

@@ -120,9 +120,6 @@ func TestToAuthenticationConfig(t *testing.T) {
 			IssuerURL:     "testIssuerURL",
 			ClientID:      "testClientID",
 		},
-		PasswordFile: &PasswordFileAuthenticationOptions{
-			BasicAuthFile: "/testBasicAuthFile",
-		},
 		RequestHeader: &apiserveroptions.RequestHeaderAuthenticationOptions{
 			UsernameHeaders:     []string{"x-remote-user"},
 			GroupHeaders:        []string{"x-remote-group"},
@@ -144,7 +141,6 @@ func TestToAuthenticationConfig(t *testing.T) {
 	expectConfig := kubeauthenticator.Config{
 		APIAudiences:                authenticator.Audiences{"http://foo.bar.com"},
 		Anonymous:                   false,
-		BasicAuthFile:               "/testBasicAuthFile",
 		BootstrapToken:              false,
 		ClientCAContentProvider:     nil, // this is nil because you can't compare functions
 		TokenAuthFile:               "/testTokenFile",