onlineddl: report an error when online ddl only matches only one regex (#2182)

[ti-chi-bot]

This is an automated cherry-pick of #2182

What problem does this PR solve?

When we mistakenly configure trash-table-rules in online ddl, downstream real table might be renamed to fake trash table.

What is changed and how it works?

Give a warning to users when they mistakenly configure only trash-table-rules or shadow-table-rules and don't execute any ddl to downstream at this time.

Check List

Tests

• Unit test
• Integration test

Side effects

• Possible performance regression
• Increased code complexity

Related changes

• Need to cherry-pick to the release branch

[ti-chi-bot]

[REVIEW NOTIFICATION]

This pull request has been approved by:

• Ehco1996

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[Ehco1996]

/verify

[lichunzhu]

/verify

[lichunzhu]

/merge

[ti-chi-bot]

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

Commit hash: 3018a6efc97369fad93f983ff3fe8d5e9e5a619e