CodeQL slowness on syntax_suggest fixed at 2.10.5

This reverts commit d152ac677c, "Make
CodeQL ignore syntax_suggest because of the performance problem".
Probably all instances seem to already have updated to 2.10.5 now.

.github/codeql/codeql-config.yml

@@ -1,7 +1,3 @@
 name: "CodeQL config for the Ruby language"
 
 languages: cpp
-
-# syntax_suggest consumes an hour.
-paths-ignore:
-  - lib/syntax_suggest