planner/core: migrate test-infra to testify for integration_test.go

[tisonkun]

What problem does this PR solve?

Issue Number: close #28412

Release note

None

[ti-chi-bot]

[REVIEW NOTIFICATION]

This pull request has been approved by:

• hawkingrei
• rebelice

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[tisonkun]

/cc @hawkingrei @xhebox @disksing

[sre-bot]

Code Coverage Details: https://codecov.io/github/pingcap/tidb/commit/ce8745274a7dd4298b9e01ae94f2bcdfb790603c

[rebelice]

/merge

[ti-chi-bot]

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

Commit hash: b3b95b4

[hawkingrei]

/run-unit-test

[ti-chi-bot]

@tisonkun: Your PR was out of date, I have automatically updated it for you.

At the same time I will also trigger all tests for you:

/run-all-tests

If the CI test fails, you just re-trigger the test that failed and the bot will merge the PR for you after the CI passes.

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