AT-9828: remove unused code

https://amplify-education.atlassian.net/browse/AT-9828

src/models/apigateway-base.ts

@@ -2,20 +2,10 @@ import DomainInfo = require("./domain-info");
 import ApiGatewayMap = require("./api-gateway-map");
 import DomainConfig = require("./domain-config");
 import {Client} from "@aws-sdk/smithy-client";
-import {ConfiguredRetryStrategy} from "@aws-sdk/util-retry";
 
 abstract class APIGatewayBase {
     public apiGateway: Client<any, any, any, any>;
 
-    public static getRetryStrategy() {
-        return new ConfiguredRetryStrategy(
-            5, // max attempts.
-            // This example sets the backoff at 100ms plus 5s per attempt.
-            // https://docs.aws.amazon.com/AWSJavaScriptSDK/v3/latest/modules/_aws_sdk_util_retry.html#aws-sdkutil-retry
-            (attempt: number) => 100 + attempt * 5000 // backoff function.
-        )
-    }
-
     abstract createCustomDomain(domain: DomainConfig): Promise<DomainInfo>;
 
     abstract getCustomDomain(domain: DomainConfig): Promise<DomainInfo>;