[Docs] Show a gray favicon in the dev mode

[weronikaolejniczak]

The purpose of this task is to show a gray favicon in the dev mode as opposed to the colored one like in Prod.

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Migrated from the internal tracker (elastic/eui-private#223) to allow external contributions.

[github-actions]

👋 Thank you for your suggestion or request! While the EUI team agrees that it's valid, it's unlikely that we will prioritize this issue on our roadmap. We'll leave the issue open if you or anyone else in the community wants to implement it by contributing to EUI. If not, this issue will auto close in one year.

Log | Bot Usage