Revert "syntax: Remove empty rules in regions"

This reverts commit a9b513a28a.

runtime/syntax/log.yaml

@@ -83,6 +83,7 @@ rules:
 - constant.string.url:
     start: "https?://"
     end: "\\s"
+    rules: []
 
 # path
 # - constant.string.url: "\\b(.+)/([^/]+)\\b"  # linux