expresssion: fix div result type infer bug if a integer type has minimum display length

[windtalker]

What problem does this PR solve?

Issue Number: close #55837

Problem Summary:
In MySQL, it support minimum display length when creating a integer type, for example, you can create table with type col1 bigint(4), it means the display length of col1 should be at least 4.
However, TiDB just treated 4 as the flen of the current type, which will cause wrong result in some cases, since 4 here does not mean the max length of col1 is 4: for example, in #55837 a column is declared as ts bigint(4), so tidb think the result type of ts/1000 is Decimal(9,4), which is obviousely wrong, and caused the wrong result.

Since the root cause of #55837 is when user declare an interger type with minimun display length, TiDB actually treated the minimum display length as the max length of the given type, a complete fix should be re-design of TiDB's support of minimum display length of integer type, which will involve a lots of work, and it's hardly to be finished within a short time. So this pr use a simple workaround to fix #55837

What changed and how does it work?

Check List

Tests

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

  • I checked and no code files have been changed.

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

Please refer to Release Notes Language Style Guide to write a quality release note.

None

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 56.7479%. Comparing base (c13eb90) to head (57b2491).
Report is 21 commits behind head on master.

Additional details and impacted files

@@                Coverage Diff                @@
##             master     #56158         +/-   ##
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- Coverage   72.9321%   56.7479%   -16.1842%     
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  Files          1611       1736        +125     
  Lines        447557     631265     +183708     
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+ Hits         326413     358230      +31817     
- Misses       101153     249372     +148219     
- Partials      19991      23663       +3672     

Flag	Coverage Δ
integration	38.2459% <100.0000%> (?)
unit	72.9667% <100.0000%> (+0.9559%)	⬆️

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Components	Coverage Δ
dumpling	52.9567% <ø> (ø)
parser	∅ <ø> (∅)
br	52.8854% <ø> (+6.9823%)	⬆️

[ti-chi-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: wshwsh12, XuHuaiyu

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Needs approval from an approver in each of these files:

• OWNERS [XuHuaiyu,wshwsh12]
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[ti-chi-bot]

[LGTM Timeline notifier]

Timeline:

• 2024-09-20 04:54:16.111982731 +0000 UTC m=+1196125.852406671: ☑️ agreed by XuHuaiyu.
• 2024-09-20 05:38:41.980514375 +0000 UTC m=+1198791.720938317: ☑️ agreed by wshwsh12.

[ti-chi-bot]

In response to a cherrypick label: new pull request created to branch release-7.5: #56211.

[ti-chi-bot]

In response to a cherrypick label: new pull request created to branch release-8.1: #56212.