chore(deps): update jest monorepo (major) (#30434)

* chore(deps): update jest monorepo

* Remove the babel-core bridge package: no longer needed in Jest 24

* Update Jest config files setup

Migrate `setupTestFrameworkScriptFile` to `setupFilesAfterEnv`: the option got renamed.

Add explicit import of the regenerator runtime. Although we run tests in recent Node and
don't transpile generators and async/await, some NPM modules (e.g., `@wordpress/api-fetch`)
are published in transpiled form that depends on the `regeneratorRuntime` global.
Jest stopped importing the regenerator runtime in v24, so we need to re-add it manually.

Co-authored-by: jsnajdr