Fix checkstyle

Author: alextwoods

core/sdk-core/src/main/java/software/amazon/awssdk/core/client/builder/SdkDefaultClientBuilder.java

@@ -112,7 +112,6 @@
 import software.amazon.awssdk.utils.AttributeMap;
 import software.amazon.awssdk.utils.AttributeMap.LazyValueSource;
 import software.amazon.awssdk.utils.Either;
-import software.amazon.awssdk.utils.Lazy;
 import software.amazon.awssdk.utils.OptionalUtils;
 import software.amazon.awssdk.utils.StringUtils;
 import software.amazon.awssdk.utils.ThreadFactoryBuilder;