[docker_otel] Use Elastic line-optimized palette for Lens charts

[smith]

Summary

• Switch Lens colorMapping.paletteId in the Docker OTel dashboard saved objects from eui_amsterdam_color_blind to elastic_brand_2023.
• This improves visual separation for multi-series line charts where the default Elastic palette can make series hard to distinguish.

Test plan

• Install/update the docker_otel integration in a test stack.
• Open [Metrics Docker] Overview and [Metrics Docker] Container Stats dashboards.
• Confirm line charts render with Elastic line-optimized colors and series are visually distinct.

Made with Cursor

[elasticmachine]

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