[release/10.0] Revert forwarding activation signal (#124879)

Backport of #124877 to release/10.0

/cc @janvorli

## Customer Impact

- [ ] Customer reported
- [x] Found internally

A recent change that was backported to .NET 10.0.4
(#124308) was found to cause
problems to vsdbg. That problem is caused by part of the change that was
actually additional to the fix that that change made and that is not
that important. That part of the change started to forward activation
signal to handlers registered before the coreclr. This change just
reverts that part.

## Regression

- [x] Yes
- [ ] No

#124308

## Testing

Local testing

## Risk

Low. It just stops forwarding the signal which was the behavior until
the recent change.

Co-authored-by: Jan Vorlicek <janvorli@microsoft.com>

Author: github-actions[bot]

src/coreclr/pal/src/exception/signal.cpp

@@ -936,20 +936,22 @@ static void inject_activation_handler(int code, siginfo_t *siginfo, void *contex
             CONTEXTToNativeContext(&winContext, ucontext);
         }
     }
-
-    // Call the original handler when it is not ignored or default (terminate).
-    if (g_previous_activation.sa_flags & SA_SIGINFO)
-    {
-        _ASSERTE(g_previous_activation.sa_sigaction != NULL);
-        g_previous_activation.sa_sigaction(code, siginfo, context);
-    }
     else
     {
-        if (g_previous_activation.sa_handler != SIG_IGN &&
-            g_previous_activation.sa_handler != SIG_DFL)
+        // Call the original handler when it is not ignored or default (terminate).
+        if (g_previous_activation.sa_flags & SA_SIGINFO)
+        {
+            _ASSERTE(g_previous_activation.sa_sigaction != NULL);
+            g_previous_activation.sa_sigaction(code, siginfo, context);
+        }
+        else
         {
-            _ASSERTE(g_previous_activation.sa_handler != NULL);
-            g_previous_activation.sa_handler(code);
+            if (g_previous_activation.sa_handler != SIG_IGN &&
+                g_previous_activation.sa_handler != SIG_DFL)
+            {
+                _ASSERTE(g_previous_activation.sa_handler != NULL);
+                g_previous_activation.sa_handler(code);
+            }
         }
     }
 }