Remove `DELETE_DEREF` bytecode instruction

Feature or enhancement

Proposal:

The DELETE_DEREF opcode can be removed and deletion implemented by the sequence:
LOAD_DEREF POP_TOP PUSH_NULL STORE_DEREF

This would free up an opcode, and, since deletion of non-locals variables is practically never used, there is no cost to doing this.

Has this already been discussed elsewhere?

This is a minor feature, which does not need previous discussion elsewhere

Linked PRs

• gh-148185

まず DELETE_DEREF opcode の処理と、関連する PR gh-148185 を確認してください。影響を受ける compiler と runtime のパスを特定し、その後、non-local の削除で提案された命令シーケンスが使用されること、および DELETE_DEREF opcode が削除されることを検証してください。