Revert part of "Core: Removed unused functions (leftovers from sd2, was needed when scripts were built as separate dll)", this part wasnt intended

This reverts commit partly e1bacef346.

src/server/game/Scripting/ScriptMgr.h

@@ -1007,7 +1007,7 @@ class ScriptMgr
                     {
                         // Get an ID for the script. An ID only exists if it's a script that is assigned in the database
                         // through a script name (or similar).
-                        uint32 id = sObjectMgr->GetScriptId(script->GetName().c_str());
+                        uint32 id = GetScriptId(script->GetName().c_str());
                         if (id)
                         {
                             // Try to find an existing script.