[BEAM-9514] For aggregate return type, use Calcite type inference ins…

[ibzib]

…tead of ZetaSQL.

ZetaSQL does not know the nullability of the return type, but the operator should.

The previous approach was to make outputs nullable if inputs were nullable, which is not generally correct.

R: @apilloud

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Post-Commit Tests Status (on master branch)

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Java
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XLang		---			---		---

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[apilloud]

LGTM

[apilloud]

Are there tests we can turn on to make sure this doesn't regress? (Or followup CLs we can merge?

[ibzib]

Are there tests we can turn on to make sure this doesn't regress? (Or followup CLs we can merge?

LOGICAL_AND is an example of a function that did not conform to the previous assumption. But it will require more work before we can merge it (#13817).

[ibzib]

I ran compliance tests on this, and some aggregate function tests are failing. For example, one such test expects an error. It was listed as ALLOW_ERROR before, and was giving this error:

java.lang.AssertionError: type mismatch:
aggCall type:
BIGINT NOT NULL
inferred type:
BIGINT

But now it does not throw any error, and instead returns a result, which is incorrect.

So in summary, this PR fixes one problem, which reveals several other unrelated problems.

[ibzib]

I added a bunch of tests for the bugs this fix uncovers.

[ibzib]

Closing this for now because it is blocked by those other bugs (BEAM-10379, BEAM-12098, BEAM-12099, BEAM-12100).