RFR: 8271419: Refactor test code for modifying CDS archive contents [v4]

[Yumin Qi]

On Mon, 2 Aug 2021 20:18:39 GMT, Calvin Cheung <ccheung at openjdk.org> wrote:

>> Yumin Qi has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   Remove Utils from import
>
> Marked as reviewed by ccheung (Reviewer).

@calvinccheung @iklam Thanks for review!

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PR: https://git.openjdk.java.net/jdk/pull/4945