gh-128982: Revert "#128982: Substitute regular expression in http.cookiejar.join_header_words for an efficient alternative (GH-128983)" and add tests (GH-130584)

* Revert "gh-128982: Substitute regular expression in `http.cookiejar.join_header_words` for an efficient alternative (GH-128983)"

This reverts commit 56e190068177855266f32a7efa329d145b279f94.

* Add tests