tidb lightning: remove the addr for the importer backend

[qiancai]

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What is changed, added or deleted? (Required)

Fix https://asktug.com/t/topic/1029587. The TiKV-importer component has been deprecated since v7.5.0 as stated in TiDB 7.5.0 Release Notes.

Which TiDB version(s) do your changes apply to? (Required)

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For details, see tips for choosing the affected versions (in Chinese).

• master (the latest development version)
• v8.3 (TiDB 8.3 versions)
• v8.2 (TiDB 8.2 versions)
• v8.1 (TiDB 8.1 versions)
• v8.0 (TiDB 8.0 versions)
• v7.5 (TiDB 7.5 versions)
• v7.1 (TiDB 7.1 versions)
• v6.5 (TiDB 6.5 versions)
• v6.1 (TiDB 6.1 versions)
• v5.4 (TiDB 5.4 versions)
• v5.3 (TiDB 5.3 versions)
• v5.2 (TiDB 5.2 versions)

What is the related PR or file link(s)?

English PR is not needed because the change had been done in pingcap/docs#14343 already,

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• Delete files
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• Might cause conflicts after applied to another branch

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@Frank945946: adding LGTM is restricted to approvers and reviewers in OWNERS files.

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[qiancai]

English PR is not needed, because the same change had been done in pingcap/docs#14343.

[ti-chi-bot]

[LGTM Timeline notifier]

Timeline:

• 2024-07-30 09:49:01.519637585 +0000 UTC m=+262857.799685654: ☑️ agreed by lance6716.
• 2024-07-31 08:26:33.779935242 +0000 UTC m=+344310.059983306: ☑️ agreed by Oreoxmt.

[qiancai]

/approve

[ti-chi-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: qiancai

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[ti-chi-bot]

In response to a cherrypick label: new pull request created to branch release-8.1: #18208.

[ti-chi-bot]

In response to a cherrypick label: new pull request created to branch release-8.2: #18209.

[ti-chi-bot]

In response to a cherrypick label: new pull request created to branch release-7.5: #18210.

[ti-chi-bot]

In response to a cherrypick label: new pull request created to branch release-8.0: #18211.