Fix regr functions result to be null when the input data is null

[8dukongjian]

Description

The result of the regr_count function should be null when the input data is null, not 0. The same problem exists with regr_avgx, regr_avgy, regr_syy, regr_sxx and regr_sxy.

presto> SELECT regr_count(c0, c1)
     -> FROM (
     ->   VALUES 
     ->     (null, null),
     ->     (null, null)
     -> ) AS tmp (c0, c1);
 _col0 
-------
   0.0 
(1 row)

Query 20240307_122037_00003_g2jsb, FINISHED, 1 node

fix #22110

Release Notes

== RELEASE NOTE ==

General Changes
* Fix the regr_count, regr_avgx, regr_avgy, regr_syy, regr_sxx, and regr_sxy functions result to be null when the input data is null, not 0. 

[8dukongjian]

@tdcmeehan Would you help review this PR?

[steveburnett]

Suggest adding a release note entry for this PR following the release notes guidelines. Perhaps something like this accurately describes the work?

== RELEASE NOTES ==

General Changes
* Fix the regr_count, regr_avgx, regr_avgy, regr_syy, regr_sxx, and regr_sxy functions result to be null when the input data is null, not 0. 

[8dukongjian]

Suggest adding a release note entry for this PR following the release notes guidelines. Perhaps something like this accurately describes the work?

== RELEASE NOTES ==

General Changes
* Fix the regr_count, regr_avgx, regr_avgy, regr_syy, regr_sxx, and regr_sxy functions result to be null when the input data is null, not 0. 

Thanks, done.

[tdcmeehan]

Please update the commit message to indicate the bugs we are fixing. Please ensure it follows our guidelines in CONTRIBUTING.md

[tdcmeehan]

If the count is not finite, should it throw?

[8dukongjian]

If the count is not finite, the result should be null, which is consistent with the behavior of the regr_count function.

[8dukongjian]

@tdcmeehan Could you help me review this, thank you.

[tdcmeehan]

@8dukongjian please rebase to remove the merge commit. Then we can merge.

[8dukongjian]

@8dukongjian please rebase to remove the merge commit. Then we can merge.

Done, Thanks!