remove vendored http-client-restricted

Removed vendored copy of http-client-restricted, and removed the
HttpClientRestricted build flag that avoided that dependency.

http-client-restricted is in Debian stable, and the i386ancient build also
uses it, so I think this vendored copy is no longer needed.

Sponsored-by: Noam Kremen on Patreon

standalone/linux/stack-i386ancient.yaml

@@ -11,7 +11,6 @@ flags:
     benchmark: false
     networkbsd: true
     gitlfs: true
-    httpclientrestricted: true
 packages:
 - '.'
 extra-deps: