RFR: 8347840: Fix testlibrary compilation warnings [v3]

[David Holmes]

On Thu, 16 Jan 2025 18:18:15 GMT, Leonid Mesnik <lmesnik at openjdk.org> wrote:

>> There few compiler warning disabled in the testlibary build.
>> They should be fixed or localized and removed from build to prevent new possible issues.
>> 
>> The main goal is to avoid new such issues in the testlibrary. 
>> Tested with tier1-5 to ensure that all tests were passed.
>
> Leonid Mesnik has updated the pull request incrementally with one additional commit since the last revision:
> 
>   revert change

Looks good. Thanks

-------------

Marked as reviewed by dholmes (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/23143#pullrequestreview-2558035645