gh-107265: Ensure de_instrument does not handle ENTER_EXECUTOR (#108366)

Python/instrumentation.c

@@ -564,6 +564,7 @@ de_instrument(PyCodeObject *code, int i, int event)
     _Py_CODEUNIT *instr = &_PyCode_CODE(code)[i];
     uint8_t *opcode_ptr = &instr->op.code;
     int opcode = *opcode_ptr;
+    assert(opcode != ENTER_EXECUTOR);
     if (opcode == INSTRUMENTED_LINE) {
         opcode_ptr = &code->_co_monitoring->lines[i].original_opcode;
         opcode = *opcode_ptr;