For lightweight-frames ensure frame is initialized in maybe_set_opcode_trace

Summary:
Not doing this causes `test.test_dynamic.TestTracing.test_after_specialization` to segfault with a trace like this:
```
* thread #1, stop reason = signal SIGSEGV
  * frame #0: 0x00000000007ac592 mmap_clone_4_python3.14`maybe_set_opcode_trace(tstate=0x0000000000a21780) at legacy_tracing.c:690
    frame #1: 0x00000000007ac344 mmap_clone_4_python3.14`_PyEval_SetTrace(tstate=0x0000000000a21780, func=(mmap_clone_4_python3.14`trace_trampoline at
 sysmodule.c:1103), arg=<function instance at 0x00007fa2830e44d0>) at legacy_tracing.c:724
    frame #2: 0x0000000000834b47 mmap_clone_4_python3.14`sys_settrace(module=<unavailable>, function=<unavailable>) at sysmodule.c:1155
    frame #3: 0x00007fa2743c2594 _cinderx.so`::_PyObject_VectorcallTstate() at pycore_call.h:169
    frame #4: 0x00007fa2743c26a6 _cinderx.so`::JITRT_Vectorcall() at jit_rt.cpp:1032
    frame #5: 0x00007fa26f086cae
```

Reviewed By: itamaro, DinoV

Differential Revision: D90545688

fbshipit-source-id: e091f8259112c845b92795dd7b211f7319b02837

Author: jbower-fb

Python/legacy_tracing.c

@@ -686,6 +686,7 @@ maybe_set_opcode_trace(PyThreadState *tstate)
     if (iframe == NULL) {
         return 0;
     }
+    _PyFrame_EnsureFrameFullyInitialized(iframe);
     PyFrameObject *frame = iframe->frame_obj;
     if (frame == NULL || !frame->f_trace_opcodes) {
         return 0;