🔥 Remove now unnecessary `shrink-to-fit` viewport directive for v4

Created by: k-utsumi

I found out after researching shrink-to-fit.

ref. https://getbootstrap.com/docs/4.5/getting-started/introduction/#responsive-meta-tag https://github.com/h5bp/html5-boilerplate/pull/2103

---

Redo #28314.