fix: engine initializes optimizer attributes at the beginning (#7410)

As in `destroy`, `self.optimizer` is called, but the error out calling
to `destroy` can happen in `__init__`, even before optimizer and
scheduler is configured. So we need to move `self.optimizer` to the top
to avoid triggering another exception.

e.g.:
```logs
  File "deepspeed/runtime/engine.py", line 453, in _configure_tensor_parallel_states
    assert self.zero_optimization_stage(
AssertionError: Currently, the compatibility between 'autotp' and 'zero_stage = 3' has not been validated
Exception ignored in: <function DeepSpeedEngine.__del__ at 0x1516c0610820>
Traceback (most recent call last):
  File "deepspeed/runtime/engine.py", line 509, in __del__
    self.destroy()
  File "deepspeed/runtime/engine.py", line 512, in destroy
    if self.optimizer is not None and hasattr(self.optimizer, 'destroy'):
  File "deepspeed/runtime/engine.py", line 621, in __getattr__
    raise AttributeError(f"'{type(self).__name__}' object has no attribute '{name}'")
AttributeError: 'DeepSpeedEngine' object has no attribute 'optimizer'
```

Signed-off-by: Hollow Man <[email protected]>

Author: HollowMan6

deepspeed/runtime/engine.py

@@ -243,6 +243,9 @@ def __init__(self,
         self._global_grad_norm = None
         self.use_ds_comm = False  # False --> Use torch.dist, True --> Use ds.comm backend.
         self.checkpoint_engine = None
+        self.optimizer = None
+        self.basic_optimizer = None
+        self.lr_scheduler = None
 
         self._is_gradient_accumulation_boundary = None
         self.scale_wrt_gas = None
@@ -313,9 +316,6 @@ def __init__(self,
             self.training_dataloader = None
 
         # Configure optimizer and scheduler
-        self.optimizer = None
-        self.basic_optimizer = None
-        self.lr_scheduler = None
         has_optimizer = False
 
         if optimizer or self.optimizer_name():