[tests] remove stray option in test lighttpd.conf

tests/lighttpd.conf

@@ -166,7 +166,6 @@ $HTTP["host"] =~ "allow\.example\.org$" {
 
 $HTTP["host"] == "etag.example.org" {
 	static-file.etags = "disable"
-	deflate.filetype = ()
 }
 
 $HTTP["host"] == "cgi.example.org" {