chore(public): remove getNullifierMembershipWitness (#5715)

Remove getNullifierMembershipWitness oracle implementation from PUBLIC since it should not be used there. Nullifier checks are done through checkNullifierExists.

yarn-project/simulator/src/public/public_execution_context.ts

@@ -1,8 +1,4 @@
-import {
-  type NullifierMembershipWitness,
-  UnencryptedFunctionL2Logs,
-  type UnencryptedL2Log,
-} from '@aztec/circuit-types';
+import { UnencryptedFunctionL2Logs, type UnencryptedL2Log } from '@aztec/circuit-types';
 import {
   CallContext,
   FunctionData,
@@ -259,16 +255,6 @@ export class PublicExecutionContext extends TypedOracle {
     return childExecutionResult.returnValues;
   }
 
-  public async getNullifierMembershipWitness(
-    blockNumber: number,
-    nullifier: Fr,
-  ): Promise<NullifierMembershipWitness | undefined> {
-    if (!this.header.globalVariables.blockNumber.equals(new Fr(blockNumber))) {
-      throw new Error(`Public execution oracle can only access nullifier membership witnesses for the current block`);
-    }
-    return await this.commitmentsDb.getNullifierMembershipWitnessAtLatestBlock(nullifier);
-  }
-
   public async checkNullifierExists(nullifier: Fr): Promise<boolean> {
     const witness = await this.commitmentsDb.getNullifierMembershipWitnessAtLatestBlock(nullifier);
     return !!witness;