fix(storybook): remove build script for payment-server's storybook

[MagentaManifold]

Because

• payment-server is no longer used and its storybook is no longer useful

This pull request

• removes the build script for payment-server's storybook so that it no longer gets built

Issue that this pull request solves

Closes: (issue number)

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Pull request overview

This PR disables building the (legacy) fxa-payments-server Storybook by removing its build-storybook script, aligning with the goal of no longer generating Storybook artifacts for an unused package.

Changes:

• Removed the build-storybook npm script from packages/fxa-payments-server/package.json so Nx/CI no longer has a build-storybook target to run for this package.

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[LZoog]

Makes sense, thank you!