fix(docs): remove duplicated characters in dev_guides

[kittimzhe]

Fix 3 duplicated-character typos in docs/dev_guides:

• api_contributing_guides/new_cpp_op_cn.md: 「变量的的 Shape」→「变量的 Shape」
• docs_contributing_guides_cn.md: 分列表里多出的一个「、」
• docs_contributing_guides_cn.md: 「CI 运行的的 log」→「CI 运行的 log」

[CLAassistant]

All committers have signed the CLA.

[kittimzhe]

Hi @Echo-Nie, a friendly ping — this trivial typo fix has been waiting for review for over a week, and it's fully ready:

• CLA signed ✅
• CI green ✅
• branch in sync with develop (no rebase needed) ✅
• 3 duplicated-character typos in docs/dev_guides (+3/−3), nothing else

Would you mind taking a look when you have a moment? Thank you!

[github-actions]

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