Remove unused config INNER_API_KEY replaced by INNER_API_KEY_FOR_PLUGIN

[bowenliang123]

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1. Is this request related to a challenge you're experiencing? Tell me about your story.

• remove the optional config INNER_API_KEY is no longer used or referenced in all the services, which has been repleaced by the required config INNER_API_KEY_FOR_PLUGIN in Introduce Plugins #13836

2. Additional context or comments

No response

3. Can you help us with this feature?

• I am interested in contributing to this feature.