RFR: 8302845: Replace finalizer usage in JNDI DNS provider with Cleaner [v2]

[Alan Bateman]

On Fri, 5 May 2023 19:08:27 GMT, Aleksei Efimov <aefimov at openjdk.org> wrote:

>> JNDI `DnsClient` has a finalize method to close its internal datagram channel selector.
>>  The change proposed here replaces it with a cleaner to close the selector once the `DnsClient`
>>   instance becomes phantom reachable. 
>> 
>> The change was tested with `jdk-tier1` to `jdk-tier3` test sets which showed no failures.
>
> Aleksei Efimov has updated the pull request incrementally with one additional commit since the last revision:
> 
>   fix comment

Marked as reviewed by alanb (Reviewer).

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PR Review: https://git.openjdk.org/jdk/pull/13837#pullrequestreview-1415346229