`prep_aria`: mask `azimuthAngle` with water mask (#1465)

* Mask azimuthAngle with water mask

Apply water mask to azimuthAngle after applying conversion factor

* Apply suggestions from code review

Co-authored-by: sourcery-ai[bot] <58596630+sourcery-ai[bot]@users.noreply.github.com>

* Conditionally apply water mask to azimuthAngle

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Co-authored-by: Zhang Yunjun <yunjunz@outlook.com>
Co-authored-by: sourcery-ai[bot] <58596630+sourcery-ai[bot]@users.noreply.github.com>