fix: reduce the usage of getSiteInfo if we already have a cachedConfig

[khendrikse]

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Summary

Netlify CLI/Buildbot uses resolveConfig to get the netlify config. It then starts the build process. During the build process netlify build uses resolveConfig again. It already has the site info at that point though. With this piece of logic we're trying to avoid additional calls to both the netlify api and the extension api. Both of which are happening inside of getSiteInfo.

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[github-actions]

This pull request adds or modifies JavaScript (.js, .cjs, .mjs) files.
Consider converting them to TypeScript.

[github-actions]

This pull request adds or modifies JavaScript (.js, .cjs, .mjs) files.
Consider converting them to TypeScript.