CLI: Fix pnpm init command

[yannbf]

Closes #

What I did

Turns out -y is not a known flag to pnpm init! It's not an interactive command like in npm, therefore I removed it!

How to test

1. On an empty dir, run pnpm init -y, watch it fail
2. Now run pnpm init, watch it succeed!

Checklist

• Make sure your changes are tested (stories and/or unit, integration, or end-to-end tests)
• Make sure to add/update documentation regarding your changes
• If you are deprecating/removing a feature, make sure to update
  MIGRATION.MD

Maintainers

• If this PR should be tested against many or all sandboxes,
  make sure to add the ci:merged or ci:daily GH label to it.
• Make sure this PR contains one of the labels below.

["cleanup", "BREAKING CHANGE", "feature request", "bug", "documentation", "maintenance", "dependencies", "other"]