Remove redundant session.commit() calls in FastAPI route handlers

[KushagraB424]

Description

The database session in the FastAPI layer is injected via the SessionDep dependency, which is backed by the create_session context manager. This context manager automatically commits the transaction when a request completes successfully.

Explicitly calling session.commit() inside the route handler is redundant and circumvents the dependency's intended transaction lifecycle management. This brings these specific route handlers in line with the codebase guideline that prohibits functions accepting a session parameter from calling commit.

Impacted Files

• airflow/api_fastapi/execution_api/routes/xcoms.py
• airflow/api_fastapi/execution_api/routes/hitl.py
• airflow/api_fastapi/core_api/routes/public/hitl.py
• airflow/api_fastapi/core_api/routes/public/backfills.py

Closes: #69492

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• Yes (Antigravity)

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