expression: fix the wrong behavior of conv function (#53681)

[ti-chi-bot]

This is an automated cherry-pick of #53681

What problem does this PR solve?

Issue Number: close #53505

Problem Summary: expression: fix the wrong behavior of conv function

What changed and how does it work?

When evaluating Constant, should always use Constant.EvalXXX() instead of accessing Constant.Value directly, otherwise there might be wrong result if it's a parameter (?).

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

[ti-chi-bot]

[LGTM Timeline notifier]

Timeline:

• 2024-07-08 09:58:05.727861891 +0000 UTC m=+265182.963095999: ☑️ agreed by AilinKid.
• 2024-07-08 16:54:18.79837266 +0000 UTC m=+290156.033606759: ☑️ agreed by winoros.

[qw4990]

/retest

[codecov]

Codecov Report

Attention: Patch coverage is 40.00000% with 3 lines in your changes missing coverage. Please review.

Please upload report for BASE (release-7.5@4f5d583). Learn more about missing BASE report.

Additional details and impacted files

@@               Coverage Diff                @@
##             release-7.5     #54354   +/-   ##
================================================
  Coverage               ?   71.9984%           
================================================
  Files                  ?       1412           
  Lines                  ?     410941           
  Branches               ?          0           
================================================
  Hits                   ?     295871           
  Misses                 ?      95188           
  Partials               ?      19882           

Flag	Coverage Δ
unit	71.9984% <40.0000%> (?)

Flags with carried forward coverage won't be shown. Click here to find out more.

Components	Coverage Δ
dumpling	53.9913% <0.0000%> (?)
parser	∅ <0.0000%> (?)
br	53.4573% <0.0000%> (?)

[ti-chi-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: AilinKid, winoros, XuHuaiyu

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Needs approval from an approver in each of these files:

• OWNERS [AilinKid,XuHuaiyu,winoros]
• pkg/expression/OWNERS [XuHuaiyu]

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[qw4990]

/retest

[qw4990]

/retest