[AIRFLOW-5729] Make InputDataConfig optional in Sagemaker's training config

[BasPH]

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Jira

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Description

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Config item InputDataConfig is optional to SageMaker, however the SageMakerTrainingOperator fails if it isn't provided (docs: https://docs.aws.amazon.com/sagemaker/latest/dg/API_CreateTrainingJob.html#SageMaker-CreateTrainingJob-request-InputDataConfig). This PR first checks if InputDataConfig is set.

Tests

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Documentation

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[codecov-io]

Codecov Report

Merging #6398 into master will decrease coverage by 0.23%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master    #6398      +/-   ##
==========================================
- Coverage   84.15%   83.91%   -0.24%     
==========================================
  Files         627      627              
  Lines       36537    36538       +1     
==========================================
- Hits        30746    30660      -86     
- Misses       5791     5878      +87

Impacted Files	Coverage Δ
airflow/contrib/hooks/sagemaker_hook.py	87.25% <100%> (+0.05%)	⬆️
airflow/kubernetes/volume_mount.py	44.44% <0%> (-55.56%)	⬇️
airflow/kubernetes/volume.py	52.94% <0%> (-47.06%)	⬇️
airflow/kubernetes/pod_launcher.py	45.25% <0%> (-46.72%)	⬇️
airflow/kubernetes/kube_client.py	33.33% <0%> (-41.67%)	⬇️
...rflow/contrib/operators/kubernetes_pod_operator.py	70.14% <0%> (-28.36%)	⬇️
airflow/jobs/local_task_job.py	85% <0%> (-5%)	⬇️
airflow/utils/dag_processing.py	58.48% <0%> (+0.32%)	⬆️
airflow/hooks/dbapi_hook.py	88.13% <0%> (+1.69%)	⬆️
airflow/utils/sqlalchemy.py	93.22% <0%> (+1.69%)	⬆️
... and 2 more

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[kaxil]

Can we add a test with and without ['InputDataConfig'], please ?

[BasPH]

@kaxil added test case without InputDataConfig