mysql(ticdc): remove error filter when check isTiDB in backend init (#11214)

[ti-chi-bot]

This is an automated cherry-pick of #11214

What problem does this PR solve?

Issue Number: close #11213

What is changed and how it works?

remove error detection in checkIsTiDB to avoid unexcept error when the downstream is different mysql-class server

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

[codecov]

Codecov Report

Attention: Patch coverage is 0% with 1 line in your changes missing coverage. Please review.

Please upload report for BASE (release-8.1@c3460e2). Learn more about missing BASE report.

Additional details and impacted files

Components	Coverage Δ
cdc	61.6247% <0.0000%> (?)
dm	51.2243% <0.0000%> (?)
engine	63.3950% <0.0000%> (?)

Flag	Coverage Δ
unit	57.3797% <0.0000%> (?)

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

@@               Coverage Diff                @@
##             release-8.1     #11258   +/-   ##
================================================
  Coverage               ?   57.3797%           
================================================
  Files                  ?        852           
  Lines                  ?     125682           
  Branches               ?          0           
================================================
  Hits                   ?      72116           
  Misses                 ?      48143           
  Partials               ?       5423           

[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

[hongyunyan]

/retest