mysql(ticdc): remove returned error and modify the log in CheckIsTiDB

[wlwilliamx]

What problem does this PR solve?

Issue Number: close #11505

What is changed and how it works?

Description:
This PR refactors the CheckIsTiDB function in response to internal discussions. Previously, the function returned an error which was not necessary, as the external callers should not care about the error of the CheckIsTiDB function due to #11213.

Changes:

1. Removed the error return type from CheckIsTiDB.
2. Replaced the error log with a warning to handle cases where querying the TiDB version fails.
3. Updated comments to explain the background and rationale for the change.

Check List

Tests

• Unit test

Questions

Will it cause performance regression or break compatibility?

No

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

No

Release note

None

[codecov]

Codecov Report

Attention: Patch coverage is 11.53846% with 23 lines in your changes missing coverage. Please review.

Project coverage is 57.7083%. Comparing base (691380d) to head (1fea471).
Report is 17 commits behind head on master.

Additional details and impacted files

Components	Coverage Δ
cdc	61.6234% <11.5384%> (+0.4332%)	⬆️
dm	51.0853% <ø> (+0.0559%)	⬆️
engine	63.4161% <ø> (+0.0282%)	⬆️

Flag	Coverage Δ
unit	57.7083% <11.5384%> (+0.2572%)	⬆️

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

@@               Coverage Diff                @@
##             master     #11506        +/-   ##
================================================
+ Coverage   57.4511%   57.7083%   +0.2572%     
================================================
  Files           851        851                
  Lines        126431     127063       +632     
================================================
+ Hits          72636      73326       +690     
+ Misses        48384      48331        -53     
+ Partials       5411       5406         -5     

[hongyunyan]

LGTM

[wlwilliamx]

/retest

[ti-chi-bot]

[APPROVALNOTIFIER] This PR is APPROVED

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

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[ti-chi-bot]

[LGTM Timeline notifier]

Timeline:

• 2024-08-21 12:49:43.857103107 +0000 UTC m=+356178.991553221: ☑️ agreed by hongyunyan.
• 2024-09-09 10:17:57.892637626 +0000 UTC m=+265147.633061566: ☑️ agreed by asddongmen.

[wlwilliamx]

/check-issue-triage-complete

[wlwilliamx]

/pull-cdc-integration-kafka-test

[wlwilliamx]

/test dm-integration-test

[wlwilliamx]

/test cdc-integration-kafka-test

[wlwilliamx]

/test cdc-integration-kafka-test