RFR: 8357178: Simplify Class::componentType [v2]

[Roger Riggs]

On Mon, 19 May 2025 00:22:08 GMT, Chen Liang <liach at openjdk.org> wrote:

>> `isArray` and null return is now redundant when `componentType` is changed to an explicit field.
>
> Chen Liang has updated the pull request incrementally with one additional commit since the last revision:
> 
>   For parity with MT.descriptorString

lgtm

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Marked as reviewed by rriggs (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/25280#pullrequestreview-2864932353