expression: implement comparison between json opaque

[YangKeao]

Signed-off-by: YangKeao yangkeao@chunibyo.icu

What problem does this PR solve?

Issue Number: close #37315

Problem Summary:

The comparison between json opaque is not implemented. They are currently comparing the .GetString of them, which will cause panic!

What is changed and how it works?

Implement the json opaque through comparing the .GetOpaque().Buf.

Check List

Tests

• Unit test
• Integration test
• Manual test (add detailed scripts or steps below)
• No code

Release note

Please refer to Release Notes Language Style Guide to write a quality release note.

Fix the issue that comparison between json opaque will cause panic

[ti-chi-bot]

[REVIEW NOTIFICATION]

This pull request has been approved by:

• xhebox
• xiongjiwei

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[xhebox]

LGTM

but please triage your issue in TiRelease, or just skip the triage of this PR.

[xiongjiwei]

/run-check-issue-triage-complete

[xiongjiwei]

/merge

[ti-chi-bot]

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

Commit hash: 0f4c693

[hawkingrei]

/run-mysql-test tidb-test=pr/1937

[xiongjiwei]

/run-mysql-test

[xiongjiwei]

/run-mysql-test tidb-test=pr/1937

[sre-bot]

Code Coverage Details: https://codecov.io/github/pingcap/tidb/commit/0f4c69355d9b8c11708d96d8a0e00450ef238730

[sre-bot]

TiDB MergeCI notify

🔴 Bad News! [2] CI still failing after this pr merged.
These failed integration tests don't seem to be introduced by the current PR.

CI Name	Result	Duration	Compare with Parent commit
idc-jenkins-ci-tidb/integration-common-test	🔴 failed 4, success 13, total 17	12 min	Existing failure
idc-jenkins-ci-tidb/common-test	🔴 failed 1, success 10, total 11	12 min	Existing failure
idc-jenkins-ci/integration-cdc-test	🟢 all 36 tests passed	36 min	Existing passed
idc-jenkins-ci-tidb/tics-test	🟢 all 1 tests passed	7 min 55 sec	Existing passed
idc-jenkins-ci-tidb/sqllogic-test-2	🟢 all 28 tests passed	6 min 54 sec	Existing passed
idc-jenkins-ci-tidb/sqllogic-test-1	🟢 all 26 tests passed	6 min 43 sec	Existing passed
idc-jenkins-ci-tidb/integration-ddl-test	🟢 all 6 tests passed	5 min 43 sec	Existing passed
idc-jenkins-ci-tidb/mybatis-test	🟢 all 1 tests passed	3 min 28 sec	Existing passed
idc-jenkins-ci-tidb/integration-compatibility-test	🟢 all 1 tests passed	3 min 6 sec	Existing passed
idc-jenkins-ci-tidb/plugin-test	🟢 build success, plugin test success	4min	Existing passed