fix(textarea): ensure that correct height is applied when rows and expandable prop are used together - FE-6810

[DipperTheDan]

This fix ensures that when the rows prop and expandable prop are used simultaneously, the textarea component renders with the correct height.

fixes #6961

Proposed behaviour

Current behaviour

Checklist

• Commits follow our style guide
• Related issues linked in commit messages if required
• Screenshots are included in the PR if useful
• All themes are supported if required
• Unit tests added or updated if required
• Playwright automation tests added or updated if required
• Storybook added or updated if required
• Translations added or updated (including creating or amending translation keys table in storybook) if required
• Typescript d.ts file added or updated if required
• Related docs have been updated if required

QA

• Tested in provided StackBlitz sandbox/Storybook
• Add new Playwright test coverage if required
• Carbon implementation matches Design System/designs
• UI Tests GitHub check reviewed if required

Additional context

I have opted to go with a Chromatic snapshot to cover us in the event of any regression happening and reintroducing this bug.

Testing instructions

• Ensure that the new Chromatic snapshot for With expandable and rows in a dialog with form is sufficient.
• No other visual or functional regressions with Textarea.
• No other visual or functional regressions with Textarea especially when minHeight, rows or expandable props are used.