fix(sdk-core): skip btc undelegate stake tx validation

skipping the verification for btc undelegate because it is just single sig

TICKET: SC-3111

Author: noel-bitgo

modules/sdk-core/src/bitgo/staking/stakingWallet.ts

@@ -160,12 +160,7 @@ export class StakingWallet implements IStakingWallet {
       if (!transaction.buildParams) {
         throw Error(`Staking transaction ${transaction.id} build params not expanded`);
       }
-      const isBtcUndelegate =
-        this.wallet.baseCoin.getFamily() === 'btc' &&
-        transaction.transactionType.toLowerCase() === 'undelegate_withdraw';
-      const wallet = isBtcUndelegate
-        ? await this.getDescriptorWallet(transaction)
-        : await this.getWalletForBuildingAndSigning();
+      const wallet = await this.extractWallet(transaction);
 
       return {
         transaction: transaction,
@@ -174,6 +169,18 @@ export class StakingWallet implements IStakingWallet {
     }
   }
 
+  private async extractWallet(transaction: StakingTransaction) {
+    return this.isBtcUndelegate(transaction)
+      ? await this.getDescriptorWallet(transaction)
+      : await this.getWalletForBuildingAndSigning();
+  }
+
+  private isBtcUndelegate(transaction: StakingTransaction) {
+    return (
+      this.wallet.baseCoin.getFamily() === 'btc' && transaction.transactionType.toLowerCase() === 'undelegate_withdraw'
+    );
+  }
+
   /**
    * Sign the staking transaction
    * @param signOptions
@@ -269,7 +276,10 @@ export class StakingWallet implements IStakingWallet {
   ): Promise<StakingSignedTransaction> {
     const builtTx = await this.build(transaction);
     // default to verifying a transaction unless explicitly skipped
-    const skipVerification = signOptions.transactionVerificationOptions?.skipTransactionVerification ?? false;
+    // skipping the verification for btc undelegate because it is just single sig
+    const skipVerification =
+      (signOptions.transactionVerificationOptions?.skipTransactionVerification || this.isBtcUndelegate(transaction)) ??
+      false;
     if (!isStakingTxRequestPrebuildResult(builtTx.result) && !skipVerification) {
       await this.validateBuiltStakingTransaction(builtTx.transaction, builtTx);
     }