feat(abstract-utxo): remove deprecated signature verification functions

Remove deprecated methods `defaultSigHashType` and `verifySignature` in favor
of using utxolib's functions directly.

BREAKING CHANGE: Consumers must now use
`utxolib.bitgo.getDefaultSigHash(network)`

Issue: BTC-2676

Co-authored-by: llm-git <[email protected]>

Author: OttoAllmendinger

modules/abstract-utxo/src/abstractUtxoCoin.ts

@@ -920,35 +920,6 @@ export abstract class AbstractUtxoCoin extends BaseCoin {
     return isReplayProtectionUnspent<TNumber>(unspent, this.network);
   }
 
-  /**
-   * @deprecated - use utxolib.bitgo.getDefaultSigHash(network) instead
-   * @returns {number}
-   */
-  get defaultSigHashType(): number {
-    return utxolib.bitgo.getDefaultSigHash(this.network);
-  }
-
-  /**
-   * @deprecated - use utxolib.bitcoin.verifySignature() instead
-   */
-  verifySignature(
-    transaction: any,
-    inputIndex: number,
-    amount: number,
-    verificationSettings: {
-      signatureIndex?: number;
-      publicKey?: string;
-    } = {}
-  ): boolean {
-    if (transaction.network !== this.network) {
-      throw new Error(`network mismatch`);
-    }
-    return utxolib.bitgo.verifySignature(transaction, inputIndex, amount, {
-      signatureIndex: verificationSettings.signatureIndex,
-      publicKey: verificationSettings.publicKey ? Buffer.from(verificationSettings.publicKey, 'hex') : undefined,
-    });
-  }
-
   /**
    * Decompose a raw psbt/transaction into useful information, such as the total amounts,
    * change amounts, and transaction outputs.