Delete all Braintree code

We never launched this, don't planning on launching it now anyway, and it's rotted over the past two years anyway.

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=202993577

java/google/registry/tools/CreateOrUpdateRegistrarCommand.java

@@ -29,7 +29,6 @@ import com.google.common.collect.ImmutableList;
 import com.google.common.collect.ImmutableSet;
 import com.google.common.collect.Sets;
 import google.registry.model.registrar.Registrar;
-import google.registry.model.registrar.Registrar.BillingMethod;
 import google.registry.model.registrar.RegistrarAddress;
 import google.registry.model.registry.Registry;
 import google.registry.tools.params.KeyValueMapParameter.CurrencyUnitToStringMap;
@@ -187,12 +186,6 @@ abstract class CreateOrUpdateRegistrarCommand extends MutatingCommand {
   )
   private Map<CurrencyUnit, String> billingAccountMap;
 
-  @Nullable
-  @Parameter(
-      names = "--billing_method",
-      description = "Method by which registry bills this registrar customer")
-  private BillingMethod billingMethod;
-
   @Nullable
   @Parameter(
       names = "--street",
@@ -367,7 +360,6 @@ abstract class CreateOrUpdateRegistrarCommand extends MutatingCommand {
         newBillingAccountMap.putAll(billingAccountMap);
         builder.setBillingAccountMap(newBillingAccountMap);
       }
-      Optional.ofNullable(billingMethod).ifPresent(builder::setBillingMethod);
       List<Object> streetAddressFields = Arrays.asList(street, city, state, zip, countryCode);
       checkArgument(
           streetAddressFields.stream().anyMatch(isNull())

java/google/registry/tools/GetKeyringSecretCommand.java

@@ -57,9 +57,6 @@ final class GetKeyringSecretCommand implements RemoteApiCommand {
     Security.addProvider(new BouncyCastleProvider());
 
     switch (keyringKeyName) {
-      case BRAINTREE_PRIVATE_KEY:
-        out.write(KeySerializer.serializeString(keyring.getBraintreePrivateKey()));
-        break;
       case BRDA_RECEIVER_PUBLIC_KEY:
         out.write(KeySerializer.serializePublicKey(keyring.getBrdaReceiverKey()));
         break;

java/google/registry/tools/UpdateKmsKeyringCommand.java

@@ -56,9 +56,6 @@ final class UpdateKmsKeyringCommand implements RemoteApiCommand {
     byte[] input = Files.readAllBytes(inputPath);
 
     switch (keyringKeyName) {
-      case BRAINTREE_PRIVATE_KEY:
-        kmsUpdater.setBraintreePrivateKey(deserializeString(input));
-        break;
       case BRDA_RECEIVER_PUBLIC_KEY:
         kmsUpdater.setBrdaReceiverPublicKey(deserializePublicKey(input));
         break;

java/google/registry/tools/params/KeyringKeyName.java

@@ -21,7 +21,6 @@ package google.registry.tools.params;
  * any secret update command such as UpdateKmsKeyringCommand.
  */
 public enum KeyringKeyName {
-  BRAINTREE_PRIVATE_KEY,
   BRDA_RECEIVER_PUBLIC_KEY,
   BRDA_SIGNING_KEY_PAIR,
   BRDA_SIGNING_PUBLIC_KEY,