web: use CSS named chunks for bundlesize observability

Created by: valerybugakov

Context

Remove content hash from CSS chunk names if WEBPACK_USE_NAMED_CHUNKS === true.

Currently, we use this env variable only for JS chunks. Having content hash in CSS chunks makes monitoring CSS bundlesize harder. See the Honeycomb dashboard.

Test plan

Run ENTERPRISE=1 NODE_ENV=production WEBPACK_USE_NAMED_CHUNKS=true yarn build and ensure that CSS chunk names do not include content hash.

App preview:

• Web
• Storybook

Check out the client app preview documentation to learn more.