[compat] Remove deprecated functions from core code

devscripts/check-porn.py

test/helper.py

test/test_YoutubeDL.py

test/test_compat.py

test/test_download.py

test/test_socks.py

test/test_youtube_signature.py

yt_dlp/YoutubeDL.py

yt_dlp/aes.py

yt_dlp/cookies.py

yt_dlp/downloader/external.py

yt_dlp/downloader/f4m.py

yt_dlp/downloader/hls.py

yt_dlp/downloader/rtmp.py

yt_dlp/extractor/abematv.py

yt_dlp/extractor/audius.py

yt_dlp/extractor/common.py

yt_dlp/extractor/commonprotocols.py

yt_dlp/extractor/curiositystream.py

yt_dlp/extractor/espn.py