Fix overlay annotation in ControlFlowGraphShared.qll

Agent-Logs-Url: https://github.com/github/codeql/sessions/011f8465-5ad3-44e2-9d84-f5314ea1afb2

Co-authored-by: owen-mc <62447351+owen-mc@users.noreply.github.com>

Author: Copilot

go/ql/lib/semmle/go/controlflow/ControlFlowGraphShared.qll

@@ -4,7 +4,7 @@
  * Everything is wrapped in `GoCfg` to avoid name conflicts with the existing
  * CFG implementation during the transition.
  */
-overlay[local?]
+overlay[local]
 module;
 
 private import codeql.controlflow.ControlFlowGraph as CfgLib