Revert "Implement Caddy-Sponsors HTTP response header" (#1866)

This reverts commit 56453e96.

caddyhttp/header/header.go

@@ -27,10 +27,6 @@ func (h Headers) ServeHTTP(w http.ResponseWriter, r *http.Request) (int, error)
 	for _, rule := range h.Rules {
 		if httpserver.Path(r.URL.Path).Matches(rule.Path) {
 			for name := range rule.Headers {
-				if name == "Caddy-Sponsors" || name == "-Caddy-Sponsors" {
-					// see EULA
-					continue
-				}
 
 				// One can either delete a header, add multiple values to a header, or simply
 				// set a header.

caddyhttp/httpserver/server.go

@@ -343,8 +343,6 @@ func (s *Server) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 	r = r.WithContext(c)
 
 	w.Header().Set("Server", caddy.AppName)
-	sponsors := "Minio, Uptime Robot, and Sourcegraph"
-	w.Header().Set("Caddy-Sponsors", "This free web server is made possible by its sponsors: "+sponsors)
 
 	status, _ := s.serveHTTP(w, r)