Removes broken support for login with email and password
Removes obsolete `prefer_combined_hls` extractor-arg
Closes#11404, Closes#11436
Authored by: bashonly
Using https://github.com/asottile/pyupgrade
1. `__future__` imports and `coding: utf-8` were removed
2. Files were rewritten with `pyupgrade --py36-plus --keep-percent-format`
3. f-strings were cherry-picked from `pyupgrade --py36-plus`
Extractors are left untouched (except removing header) to avoid unnecessary merge conflicts