improve: Reduce the number of layers in the storefront-api Dockerfile.

[EdwinBetanc0urt]

Taking into account the official docker documentation and best practices the number of Dockerfile layers for storefront-api with node.js is reduced.

Reference information: https://docs.docker.com/develop/develop-images/dockerfile_best-practices/#minimize-the-number-of-layers

Related issues

Short description and why it's useful

Taking into account the official docker documentation and best practices the number of Dockerfile layers for storefront-api with node.js is reduced.

Reference information: https://docs.docker.com/develop/develop-images/dockerfile_best-practices/#minimize-the-number-of-layers

Screenshots of visual changes before/after (if there are any)

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