We have too many helper scripts in the LayoutTests directory that do the same thing.

Ideally, we should have smaller set of well-documented and maintained ones.

This bug is for tracking related efforts.

Examples:

Cookie setting
(for some tests, the directory to place the script matters. So, not all can be cleaned up)
http/tests/cookies/resources/setCookies.cgi
http/tests/security/resources/set-cookie.php
http/tests/inspector/network/resources/set-cookie.php
http/tests/media/resources/setCookie.cgi
http/tests/htmlimports/resources/cookie.cgi

Redirect response generation
http/tests/security/resources/redir.php
http/tests/misc/redirect.php
http/tests/resources/redirect.php
http/tests/xmlhttprequest/resources/redirect.php
http/tests/eventsource/resources/redirect.php
http/tests/serviceworker/resources/redirect.php
...