Add aws_conn_id to template_fields in Amazon S3 operators (#35259)

[divijaksolves]

closes: #35259

Description

This PR adds aws_conn_id to template_fields in S3CreateObjectOperator to enable Jinja templating support for dynamic connection IDs.

Testing

Tested locally via Breeze with:
pytest providers/amazon/tests/unit/amazon/aws/operators/test_s3.py
All 79 tests passed successfully.

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[boring-cyborg]

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[SameerMesiah97]

Since this changes template_fields, should test_template_fields be updated to include a templated aws_conn_id?

[divijaksolves]

Thanks for the review! Updated test_template_fields in test_s3.py to include a templated aws_conn_id="aws_{{ ds }}" and verified that all 79 tests pass locally via Breeze.