`BatchClient.begin_terminate_job` crashes with default value for option parameter

• Package Name: azure-batch
• Package Version: 15.1.0
• Operating System: Ubuntu 24.04
• Python Version: 3.13.13

Describe the bug
BatchClient.begin_terminate_job() doesn't correctly handle the case where you call it with the default value for the options parameter. It also fails identically with a default-constructed BatchJobTerminateOptions passed to it. The stack trace is:

  File "/opt/hostedtoolcache/Python/3.13.13/x64/lib/python3.13/site-packages/azure/batch/_operations/_patch.py", line 1008, in begin_terminate_job
    self._terminate_job_internal(
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~^
        job_id,
        ^^^^^^^
    ...<9 lines>...
        **kwargs,
        ^^^^^^^^^
    ),
    ^
  File "/opt/hostedtoolcache/Python/3.13.13/x64/lib/python3.13/site-packages/azure/core/tracing/decorator.py", line 119, in wrapper_use_tracer
    return func(*args, **kwargs)
  File "/opt/hostedtoolcache/Python/3.13.13/x64/lib/python3.13/site-packages/azure/batch/_operations/_operations.py", line 5806, in _terminate_job_internal
    _request = build_batch_terminate_job_internal_request(
        job_id=job_id,
    ...<11 lines>...
        params=_params,
    )
  File "/opt/hostedtoolcache/Python/3.13.13/x64/lib/python3.13/site-packages/azure/batch/_operations/_operations.py", line 1071, in build_batch_terminate_job_internal_request
    _headers["content-type"] = _SERIALIZER.header("content_type", content_type, "str")
                               ~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/opt/hostedtoolcache/Python/3.13.13/x64/lib/python3.13/site-packages/azure/batch/_utils/serialization.py", line 758, in header
    output = self.serialize_data(data, data_type, **kwargs)
  File "/opt/hostedtoolcache/Python/3.13.13/x64/lib/python3.13/site-packages/azure/batch/_utils/serialization.py", line 777, in serialize_data
    raise ValueError("No value for given attribute")
ValueError: No value for given attribute

From this we can determine what the happens to cause this bug:

1. _terminate_job_internal only sets content_type if options is true (in the bool sense). Neither the default value (None) nor the default-constructed BatchJobTerminateOptions evaluate to true. So content_type ends up equal to None.
2. build_batch_terminate_job_internal_request will always set the content-type header, regardless of if content-type was actually provided (_headers["content-type"] = _SERIALIZER.header("content_type", content_type, "str")). This should be guarded by an if statement like all of the other headers are.

To Reproduce
Steps to reproduce the behavior:

1. Call BatchClient.begin_terminate_job with the default value for options (or with a default constructed BatchJobTerminateOptions).
2. Observe the crash above.

Expected behavior
The default value should work.

Screenshots
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Additional context
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