Revert "chore(gatsby): Make `plugins` in `PluginOptions` type optional (#36351)"
Revert "chore(gatsby): Make `plugins` in `PluginOptions` type optional (#36351)"

This reverts commit a2fa5a2ded1071e9fb9c32fe2726236bcb2914c2.

gatsbyjs/gatsby,gatsbyjs/gatsby,gatsbyjs/gatsby,gatsbyjs/gatsby,gatsbyjs/gatsby,gatsbyjs/gatsby