feat: Fall back to datasets' "extra" if arg extra is empty

[zhenglin-charlie-li]

fix: #37006

Fall back to datasets' "extra" if arg extra is empty

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[hussein-awala]

Could you add a test for this change?

[zhenglin-charlie-li]

@hussein-awala Thanks for your review! I have added some test cases.

[jedcunningham]

Personally, I don't think the dataset extra is a good fallback for a dataset event's extra. I see those extras as being different.

[dirrao]

Looks like extras are reserved for future use. May be its worth to pass information about partition.

[uranusjr]

See #37810 and issues and PRs linked in it (including in comments). I’ll close this for now; we can always reopen if this is the way to do (which is unlikely).