mounter(ticdc): fix truncate table partition cause mounter failed issue (#10528)

[ti-chi-bot]

This is an automated cherry-pick of #10528

What problem does this PR solve?

Issue Number: close #10522

What is changed and how it works?

like truncate table logic, when a table partition is truncated , CDC should add this partition ID to the memory map, then get a key encoded by this partition ID, mounted should ignore it, otherwise mourner will failed to decode the key.

Check List

Tests

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

Questions

Will it cause performance regression or break compatibility?

Do you need to update user documentation, design documentation or monitoring documentation?

Release note

`None`.

[ti-chi-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: sdojjy

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