Minor VSA i18n and create value stream form components refactor

What does this MR do and why?

Implements some follow-up frontend work for VSA

• #295177 (closed)
• #331194 (closed)

This MR cleans up some of the i18n strings used for the VSA custom stage form and also re-organizes some of the custom stage form fields into separate components.

Screenshots or screen recordings

• No new visual changes
• A UI polish minor fix for the extra whitespace and vertical alignment of the stage actions

Before	After

How to set up and validate locally

Numbered steps to set up and validate the change are strongly suggested.

Run the update jest and RSpec tests in the MR.

MR acceptance checklist

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