gatsby: [gatsby-recipes] Remove duplicate Babel install

The package remark-mdxjs is deprecated and no longer being published:

https://github.com/mdx-js/mdx/tree/main/packages/remark-mdxjs

According to its README its behaviour is now included in remark-mdx.

remark-mdxjs had an unranged outdated @babel/core dependency. The result is an entire second Babel install when installing Gatsby.

I think these lines should all be safely removable:

https://github.com/gatsbyjs/gatsby/blob/df3f184ee9ea1367726bd52dc4b6f130b8fa2c59/packages/gatsby/package.json#L241 https://github.com/gatsbyjs/gatsby/blob/df3f184ee9ea1367726bd52dc4b6f130b8fa2c59/packages/gatsby-recipes/package.json#L53 https://github.com/gatsbyjs/gatsby/blob/df3f184ee9ea1367726bd52dc4b6f130b8fa2c59/packages/gatsby-recipes/package.json#L122 https://github.com/gatsbyjs/gatsby/blob/54d4721462b9303fed723fdcb15ac5d72e103778/packages/gatsby-recipes/src/parser/index.js#L3 https://github.com/gatsbyjs/gatsby/blob/54d4721462b9303fed723fdcb15ac5d72e103778/packages/gatsby-recipes/src/parser/index.js#L54

There are probably other references to the package to clean up as well.