[Fix] Move ScheduleBatch out of SamplingInfo

[merrymercy]

We can get regex info during get_model_worker_batch, so we do not need to keep a reference of ScheduleBatch in SamplingInfo

[qeternity]

This seems to have broken constrained generation:

  File "/root/sglang/sglang/python/sglang/srt/model_executor/model_runner.py", line 520, in sample
    sampling_info.update_regex_vocab_mask()
  File "/root/sglang/sglang/python/sglang/srt/sampling/sampling_batch_info.py", line 123, in update_regex_vocab_mask
    self.vocab_mask[i].fill_(1)
    ~~~~~~~~~~~~~~~^^^
IndexError: index 2 is out of bounds for dimension 0 with size 2

Killed
[rank0]:W1004 19:16:06.465000 133394662926016 torch/_inductor/compile_worker/subproc_pool.py:126] SubprocPool unclean exit
/usr/lib/python3.11/multiprocessing/resource_tracker.py:123: UserWarning: resource_tracker: process died unexpectedly, relaunching.  Some resources might leak.
  warnings.warn('resource_tracker: process died unexpectedly, '
Traceback (most recent call last):
  File "/usr/lib/python3.11/multiprocessing/resource_tracker.py", line 239, in main
    cache[rtype].remove(name)
KeyError: '/mp-ieivjla9'

[merrymercy]

Fixed by #1634