Revert "[Flink] disable operator chaining in validatesRunner"

[jto]

This reverts commit 2c01ac0 which was not required.

Followup of #32440

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[kennknowles]

I'll bump the tests to get them green just to keep it clean, unless it turns out to be the classic flakes. It seemed to have failed on pulling licenses this time.

[kennknowles]

If you mark this as no longer a draft, I can merge.

[jto]

@kennknowles done :)

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