Proxito: deprecate serving README.html by default

[humitos]

We are currently serving /README.html and <path>/README.html in

readthedocs.org/readthedocs/proxito/views/serve.py

Lines 301 to 327 in e85ee7d

	# First, check for dirhtml with slash
	for tryfile in ("index.html", "README.html"):
	storage_filename_path = build_media_storage.join(
	storage_root_path,
	f"{filename}/{tryfile}".lstrip("/"),
	)
	log.debug("Trying index filename.")
	if build_media_storage.exists(storage_filename_path):
	log.info("Redirecting to index file.")
	# Use urlparse so that we maintain GET args in our redirect
	parts = urlparse(proxito_path)
	if tryfile == "README.html":
	new_path = parts.path.rstrip("/") + f"/{tryfile}"
	else:
	new_path = parts.path.rstrip("/") + "/"
	# `proxito_path` doesn't include query params.`
	query = urlparse(request.get_full_path()).query
	new_parts = parts._replace(
	path=new_path,
	query=query,
	)
	redirect_url = new_parts.geturl()
	# TODO: decide if we need to check for infinite redirect here
	# (from URL == to URL)
	return HttpResponseRedirect(redirect_url)

This is not a standard behavior and we have it there because of pretty old compatibility reasons. I'd like to deprecate this and remove this "feature" if possible. As a first step, I added the tryfile= argument in the log line in #9983 to start tracking this and check how many projects are using this non-standard hosting feature. We can then check this via New Relic, analyze and decide what to do.

[stsewd]

We have 340 projects in .org and 1 in .com relying on this https://onenr.io/0BQ1Gv2BMRx

[agjohnson]

Count has gone down in the last year: 239

https://onenr.io/0BR6Zzk5GRO

[humitos]

Cool. I checked this today and we have 227.

[humitos]

Email sent today.

[humitos]

Work done in #11348