`RestJsonWithoutBodyEmptyInputExpectsEmptyContentType:MalformedRequest` failing after smithyVersion=1.53.0

[trivikr]

Checkboxes for prior research

• I've gone through Developer Guide and API reference
• I've checked AWS Forums and StackOverflow.
• I've searched for previous similar issues and didn't find any solution.

Describe the bug

Issue is for team tracking

Regression Issue

• Select this option if this issue appears to be a regression.

SDK version number

N/A

Which JavaScript Runtime is this issue in?

Node.js

Details of the browser/Node.js/ReactNative version

All

Reproduction Steps

Enable the test skipped in #6906, and run protocol tests.

Observed Behavior

Protocol test RestJsonWithoutBodyEmptyInputExpectsEmptyContentType:MalformedRequest fails.

Expected Behavior

Protocol test RestJsonWithoutBodyEmptyInputExpectsEmptyContentType:MalformedRequest should succeed.

Possible Solution

No response

Additional Information/Context

No response