planner: fix panic when prepare and execute the insert on duplicate (#37924)

[ti-chi-bot]

This is an automated cherry-pick of #37924

What problem does this PR solve?

Issue Number: close #37187

Problem Summary:
The prepare and execute statements both will build the plan. But some code path in planBuilder have some assumptions about they only execute once.

What is changed and how it works?

1. Record the actualColLen in last.InsertStmt for reusing.
2. Initlizate the actualColLen to 0 not 1. Because it's safe and easy to handle.

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

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

None

[ti-chi-bot]

[REVIEW NOTIFICATION]

This pull request has been approved by:

• fzzf678
• winoros

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[Reminiscent]

/merge

[ti-chi-bot]

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

Commit hash: f800e5c