Removed must-init requirement for GS Cookies (#50702)

The cookie is always initialized in the prolog, where no user code is allowed.
There should be no GC concerns either as the prolog is not interruptible.

src/coreclr/jit/compiler.hpp

@@ -4181,7 +4181,7 @@ inline void Compiler::CLR_API_Leave(API_ICorJitInfo_Names ename)
 bool Compiler::fgVarIsNeverZeroInitializedInProlog(unsigned varNum)
 {
     LclVarDsc* varDsc = lvaGetDesc(varNum);
-    bool result = varDsc->lvIsParam || lvaIsOSRLocal(varNum) || (opts.IsOSR() && (varNum == lvaGSSecurityCookie)) ||
+    bool       result = varDsc->lvIsParam || lvaIsOSRLocal(varNum) || (varNum == lvaGSSecurityCookie) ||
                   (varNum == lvaInlinedPInvokeFrameVar) || (varNum == lvaStubArgumentVar) || (varNum == lvaRetAddrVar);
 
 #if FEATURE_FIXED_OUT_ARGS