mounter(ticdc): fix decoding when upstream doesn't enable new collation

[lidezhu]

What problem does this PR solve?

Issue Number: close #11371

What is changed and how it works?

Explicitly call collate.SetNewCollationEnabledForTest(false) before run cdc.

Previously, this function was called in a tidb package. But it was removed as described in pingcap/tidb#52191 (comment).

If the upstream doesn't enable new collation, the primary key is not encoded in the value part when the table is a cluster index table. And we rely on the following line to decode the primary key.

tiflow/cdc/entry/mounter.go

Line 301 in 2db0922

datums, err = tablecodec.DecodeHandleToDatumMap(

But this line only decode the primary key when the global variable newCollationEnabled in tidb package is false. (It means collate.SetNewCollationEnabledForTest(false) must be called.)

Check List

Tests

• Integration test

Questions

Will it cause performance regression or break compatibility?

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

Release note

Fix the issue that TiCDC cannot correctly decode primary key of table with cluster index when the upstream does not enable new collation.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 57.6033%. Comparing base (7ddb1a3) to head (715e8e4).

Additional details and impacted files

Components	Coverage Δ
cdc	61.3676% <ø> (+0.0127%)	⬆️
dm	51.2071% <ø> (+0.0100%)	⬆️
engine	63.4020% <ø> (+0.0282%)	⬆️

Flag	Coverage Δ
unit	57.6033% <ø> (+0.0134%)	⬆️

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

@@               Coverage Diff                @@
##             master     #11370        +/-   ##
================================================
+ Coverage   57.5899%   57.6033%   +0.0134%     
================================================
  Files           849        849                
  Lines        126286     126286                
================================================
+ Hits          72728      72745        +17     
+ Misses        48144      48128        -16     
+ Partials       5414       5413         -1     

[lidezhu]

/retest

[flowbehappy]

Add more comment to explain why we need to call this function.

[lidezhu]

Added.

[lidezhu]

/test verify

[ti-chi-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: asddongmen, CharlesCheung96

The full list of commands accepted by this bot can be found here.

The pull request process is described here

Needs approval from an approver in each of these files:

• OWNERS [CharlesCheung96,asddongmen]

Approvers can indicate their approval by writing /approve in a comment
Approvers can cancel approval by writing /approve cancel in a comment

[ti-chi-bot]

[LGTM Timeline notifier]

Timeline:

• 2024-07-02 10:56:19.669055013 +0000 UTC m=+1321906.154543845: ☑️ agreed by CharlesCheung96.
• 2024-07-02 14:06:05.852061112 +0000 UTC m=+1333292.337549941: ☑️ agreed by asddongmen.

[ti-chi-bot]

In response to a cherrypick label: new pull request created to branch release-8.1: #11378.

[ti-chi-bot]

In response to a cherrypick label: new pull request created to branch release-8.2: #11379.