drainer: skip resource group ddl

[BornChanger]

What problem does this PR solve?

Issue Number: close #1221

What is changed and how it works?

Skip resource group related ddl statements

Check List

Tests

• Unit test

Code changes

• N/A

Side effects

• N/A

Related changes

• N/A

Release note

• No release note

[ti-chi-bot]

[REVIEW NOTIFICATION]

This pull request has been approved by:

• GMHDBJD
• lichunzhu

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[lichunzhu]

LGTM

[GMHDBJD]

LGTM

[lichunzhu]

/merge

[ti-chi-bot]

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

Commit hash: 688ad6a

[lichunzhu]

/cherry-pick release-7.0

[ti-chi-bot]

@lichunzhu: new pull request created to branch release-7.0: #1223.

In response to this:

/cherry-pick release-7.0

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