gh-76785: Avoid Pickled TracebackException for Propagated Subinterpreter Exceptions (gh-113036)

We need the TracebackException of uncaught exceptions for a single purpose: the error display.  Thus we only need to pass the formatted error display between interpreters.  Passing a pickled TracebackException is overkill.

Include/internal/pycore_crossinterp.h

@@ -188,8 +188,7 @@ typedef struct _excinfo {
         const char *module;
     } type;
     const char *msg;
-    const char *pickled;
-    Py_ssize_t pickled_len;
+    const char *errdisplay;
 } _PyXI_excinfo;