perf: update template renderer paths to use package qualifiers

[brettlangdon]

Avoid unnecessary template lookup failures by specifying full package paths for all template renderers. Previously, for endpoints like /simple/<package>, the template resolver would first attempt to find 'warehouse.api:api/simple/detail.html' which would always fail, then fall back to 'templates/api/simple/detail.html'. By using explicit package qualifiers like 'warehouse:templates/api/simple/detail.html', we skip the initial failed lookup and exception handling.

This provides a small performance optimization by eliminating known failed disk lookups, as well as avoiding exception traceback generation when ddtrace is enabled (for attaching the traceback to the span metadata).

Testing locally, the template load time goes from ~830us to ~80us, and template rendering time goes from ~4ms to ~3.7ms... a small optimization, but an easy win.

[brettlangdon]

What should we do about:

warehouse/warehouse/config.py

Lines 728 to 733 in 3a1f8c8

	# We'll store all of our templates in one location, warehouse/templates
	# so we'll go ahead and add that to the Jinja2 search path.
	config.add_jinja2_search_path("warehouse:templates", name=".html")
	config.add_jinja2_search_path("warehouse:templates", name=".txt")
	config.add_jinja2_search_path("warehouse:templates", name=".xml")

Is this proposed change even desired for the minimal gain vs having the default search path?

[brettlangdon]

An alternative here is to move all the templates into their respective module paths, e.g. warehouse/templates/api/simple/detail.html -> warehouse/api/templates/simple/detail.html and then update renderer="templates/simple/detail.html" (since warehouse.api:will get prepended to all template lookups by default which don't have:` in the name)