expression, planner: skip isNullRejected check when contain outer not after PushDownNot

[rebelice]

What problem does this PR solve?

Issue Number: close #20510

Problem Summary:

The first step to check isNullRejected is to execute PushDownNot. And the correctness of isNullRejected depends on PushDownNot. But we currently cannot handle complex situations in PushDownNot correctly. eg. "not(0+(t1.a = 1 and t2.a = 2))". So at this time, isNullRejected will get the wrong result.

What is changed and how it works?

After PushDownNot, we check if there is outer not. If yes, we skip isNullRejected and return false.

Check List

Tests

• Unit test
• Integration test
• Manual test (add detailed scripts or steps below)
• No code

Side effects

• Performance regression: Consumes more CPU
• Performance regression: Consumes more Memory
• Breaking backward compatibility

Documentation

• Affects user behaviors
• Contains syntax changes
• Contains variable changes
• Contains experimental features
• Changes MySQL compatibility

Release note

Fixed some cases where `letf join` was incorrectly converted to `innor join`.

[ti-chi-bot]

[REVIEW NOTIFICATION]

This pull request has been approved by:

• Yisaer
• winoros

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[sre-bot]

Code Coverage Details: https://codecov.io/github/pingcap/tidb/commit/28d4ae096b598cab686f83a07d26adae08577eb3

[rebelice]

/run-unit-test

[Yisaer]

lgtm

[winoros]

/merge

[ti-chi-bot]

This pull request has been accepted and is ready to merge.

Commit hash: aeea3ad

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