Chore: enable prefer-regex-literals in eslint codebase #12268
This is a breaking change from the perspective of the eslint-config-eslint package, but that doesn't mean we need to hold this behind the ESLint major release.
We can release breaking changes to eslint-config-eslint more frequently, because in theory, only the ESLint team needs to update packages to consume the new configuration. And even if not, users have to choose to use eslint-config-eslint (and install it as its own package), so users should know the semver rules and should understand what they are choosing to do if they use that package.
On the other hand, updating eslint:recommended changes the recommended experience right in ESLint itself and it's not a separate package. So any changes made there must be semver-major in ESLint itself (although there are exceptions for removing rules from recommended, noted explicitly in our semver policy).