[python] chore: Simplify async/non-async api method templates

[robertschweizer]

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@multani @wing328

[multani]

Looks good to me!

[wing328]

cc @cbornet (2017/09) @tomplus (2018/10) @krjakbrjak (2023/02) @fa0311 (2023/10) @multani (2023/10)

[wing328]

lgtm too