sink: fix codec json encoding with non binary string (#2764)

[ti-chi-bot]

This is an automated cherry-pick of #2764

What problem does this PR solve?

Close #2758

Note we still don't known in which scenario the column value is string instead of []byte, need more investigation.

What is changed and how it works?

The column value type of mysql.TypeString, mysql.TypeVarString, mysql.TypeVarchar could be either string or []byte, we should consider both of these two types when converting a row column value to json encoding.

Check List

Tests

• Unit test
• Integration test

Release note

Fix json encoding could panic when processing a string type value in some cases.

[ti-chi-bot]

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[amyangfei]

/merge

[ti-chi-bot]

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

Commit hash: 5d74d46

[amyangfei]

/run-integration-tests

[amyangfei]

/run-integration-tests

[amyangfei]

/run-integration-tests

[amyangfei]

/run-integration-tests

[codecov-commenter]

Codecov Report

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