Rework addressing code review feedback in smithy-rs#3859 (#3860)

## Motivation and Context

1dbf37a
didn't address [code review
feedback](#3859 (comment))
correctly. This PR will fix it.

## Testing
Tests in CI

----

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choice._

Author: ysaito1001

aws/sdk/integration-tests/ec2/tests/paginators.rs

@@ -18,11 +18,11 @@ fn stub_config(http_client: impl HttpClient + 'static) -> Config {
         .build()
 }
 
-fn validate_query_string(expected: &str, actual: &str) {
-    let expected = expected.split('&').collect::<HashSet<&str>>();
-    let actual = actual.split('&').collect::<HashSet<&str>>();
+fn validate_query_string(expected_str: &str, actual_str: &str) {
+    assert_eq!(expected_str.len(), actual_str.len());
+    let expected = expected_str.split('&').collect::<HashSet<_>>();
+    let actual = actual_str.split('&').collect::<HashSet<_>>();
     assert_eq!(expected, actual);
-    assert_eq!(expected.len(), actual.len());
 }
 
 /// See https://github.com/awslabs/aws-sdk-rust/issues/391