Add hints.mostly-unused = true to aws-sdk-lambda and aws-sdk-rds (#4249)

Author: aws-sdk-rust-ci

.changelog/hints-mostly-unused-lambda-rds.md

@@ -0,0 +1,13 @@
+---
+applies_to:
+  - aws-sdk-rust
+  - client
+authors:
+  - joshtriplett
+breaking: false
+new_feature: true
+bug_fix: false
+---
+Enable `hints.mostly-unused = true` for `aws-sdk-lambda` (taking a release
+build from 57s to 40s) and `aws-sdk-rds` (taking a release build from 1m34s to
+49s).

aws/sdk-codegen/src/main/kotlin/software/amazon/smithy/rustsdk/AwsCodegenDecorator.kt

@@ -117,6 +117,8 @@ val DECORATORS: List<ClientCodegenDecorator> =
                 "com.amazonaws.cloudformation#CloudFormation",
                 "com.amazonaws.dynamodb#DynamoDB_20120810",
                 "com.amazonaws.ec2#AmazonEC2",
+                "com.amazonaws.lambda#AWSGirApiService",
+                "com.amazonaws.rds#AmazonRDSv19",
                 "com.amazonaws.s3#AmazonS3",
                 "com.amazonaws.sns#AmazonSimpleNotificationService",
                 "com.amazonaws.sqs#AmazonSQS",