Remove deprecated Dataset aliases from airflow.__init__

[SHIVANSH-ux-ys]

Fixes #68352

[boring-cyborg]

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[jroachgolf84]

Are there any other places where changes might need to be made?

[viiccwen]

Found the same issue, cc @Lee-W to review it.

[viiccwen]

IMO, it's a breaking change, should we add a .srt significant newsfragment?

[Lee-W]

yep, let's add a newsfragment for this

[Lee-W]

close as #70154 merged