[4.0.0-alpha7] BUG: `.htmx-request` should be preserved when the HX-Redirect header is set

[YamiOdymel]

This behavior exists in 2.0.8 but seems to have been forgotten in 4.0.0 alpha.

The .htmx-request class should be preserved because there is a brief gap between the request finishing and the page redirecting.

#1925
#2784

EDIT: Also the hx-disable 🤔?