MPP-3597: Fix mobile sizing of step two in free user onboarding

[rafeerahman]

This PR fixes MPP-3597.

Bug description

See the picture below

Screenshot of fix

How to test

• Sign in to a free user with onboarding_free_state = 0.
• Go to /accounts/profile?utm_campaign=relay-onboarding&utm_source=relay-onboarding&utm_medium=email
• Go to the second step of this onboarding by clicking generate new mask.
• Using devtools, click on mobile view and set the width to 360px.
• Verify that there is no extra space by scrolling horizontally to the right.

Checklist (Definition of Done)

• Product Owner accepted the User Story (demo of functionality completed) or waived the privilege.
• All acceptance criteria are met.
• Jira ticket has been updated (if needed) to match changes made during the development process.
• I've added or updated relevant docs in the docs/ directory
• Jira ticket has been updated (if needed) with suggestions for QA when this PR is deployed to stage.
• All UI revisions follow the coding standards, and use Protocol tokens where applicable (see /frontend/src/styles/tokens.scss).
• Commits in this PR are minimal and have descriptive commit messages.
• l10n changes have been submitted to the l10n repository, if any.

[lloan]

Awesome job - was this only affecting iOS devices?

[rafeerahman]

Awesome job - was this only affecting iOS devices?

No, was affecting all devices