Replace dynamic error message with static "Access Denied"

[kwondh5217]

Motivation

• HttpStatusServerAccessDeniedHandler previously returned the exception message,
  which could expose sensitive information.
• This PR ensures that the handler always returns a static "Access Denied" message.

Modification

• Updated HttpStatusServerAccessDeniedHandler to return a static message.
• Updated tests to verify the response body.

Result

Closes gh-16514