planner: revise sync load error msg

[Yisaer]

Signed-off-by: yisaer [email protected]

What problem does this PR solve?

Issue Number: close #xxx

Problem Summary:

What is changed and how it works?

Check List

Tests

• No code

Release note

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None

[ti-chi-bot]

[REVIEW NOTIFICATION]

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• hawkingrei
• xuyifangreeneyes

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[hawkingrei]

/merge

[ti-chi-bot]

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

Commit hash: 1994757

[sre-bot]

TiDB MergeCI notify

✅ Well Done! New fixed [1] after this pr merged.

CI Name	Result	Duration	Compare with Parent commit
idc-jenkins-ci/integration-cdc-test	🔴 failed 1, success 38, total 39	19 min	Existing failure
idc-jenkins-ci-tidb/mybatis-test	🔴 failed 1, success 0, total 1	10 min	Existing failure
idc-jenkins-ci-tidb/sqllogic-test-1	✅ all 26 tests passed	4 min 11 sec	Fixed
idc-jenkins-ci-tidb/common-test	🟢 all 11 tests passed	15 min	Existing passed
idc-jenkins-ci-tidb/integration-common-test	🟢 all 17 tests passed	12 min	Existing passed
idc-jenkins-ci-tidb/tics-test	🟢 all 1 tests passed	5 min 39 sec	Existing passed
idc-jenkins-ci-tidb/integration-ddl-test	🟢 all 6 tests passed	4 min 31 sec	Existing passed
idc-jenkins-ci-tidb/sqllogic-test-2	🟢 all 28 tests passed	4 min 21 sec	Existing passed
idc-jenkins-ci-tidb/integration-compatibility-test	🟢 all 1 tests passed	2 min 50 sec	Existing passed
idc-jenkins-ci-tidb/plugin-test	🟢 build success, plugin test success	4min	Existing passed