(bugfix) make resources work with observe()

[dpeng817]

observe() currently doesn't work when you have resources required on the observable asset, despite there being a resources arg. This is because build_assets_job expects a fully resolved list of resource definitions, which observe() relies on the Definitions object to provide. Fix by switching to define_asset_job.

How I tested this Added a test that explicitly adds resource requirements to the observable source asset. Went from failing to not failing after this change.

[dpeng817]

Current dependencies on/for this PR:

• #19698 : 5 dependent PRs (#19691 , #19700 , #19718 and 2 others)
• #19695 👈
• master

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