RFR: 8344321: GenShen: Fix various sonar scan warnings

[Aleksey Shipilev]

On Tue, 19 Nov 2024 18:19:47 GMT, William Kemper <wkemper at openjdk.org> wrote:

> Various sonar warnings are fixed: 
> * unused variables removed
> * implicit casts made explicit
> * members are all initialized

Marked as reviewed by shade (Committer).

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PR Review: https://git.openjdk.org/shenandoah/pull/544#pullrequestreview-2446325003