CLI: Do not use legacy-peer-deps for npm

[IanVS]

Issue: #18298

What I did

Removed the use of --legacy-peer-deps from npm commands, since it is no longer needed with storybook 7.0+. The npm7 migration was removed previously.

How to test

• Is this testable with Jest or Chromatic screenshots?
• Does this need a new example in the kitchen sink apps?
• Does this need an update to the documentation?

If your answer is yes to any of these, please make sure to include it in your PR.

[shilman]

Woohoo! 🎉

[miallo]

Nice! Thanks a lot! That is great :)

I ran npx sb upgrade --prerelease and it installed 7.0.0-beta.19, but I am still getting the prompt

We've detected you are running npm 8.5.0
which has peer dependency semantics which Storybook is incompatible with.
In order to work with Storybook's package structure, you'll need to run npm with the
--legacy-peer-deps=true flag. We can generate an .npmrc which will do that automatically.
More info: #18298

Unfortunately I don't know where this prompt is coming from, so I don't know where to ask...

[IanVS]

When you run npx sb, that's actually running the version of the CLI from 6.5. To run the latest-and-greatest for 7.0, use npx sb@next instead.