RFR: 8339519: Remove size field from instructions

[Adam Sotona]

On Thu, 5 Sep 2024 23:02:16 GMT, Chen Liang <liach at openjdk.org> wrote:

> `AbstractInstruction` has a redundant `size` field unnecessary for the majority of instructions. We should add this field to the 2 switch instructions that need it only.

Looks good to me.

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Marked as reviewed by asotona (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/20880#pullrequestreview-2285235940