ignore err msg:no available connections

[vivid392845427]

What problem does this PR solve?

admin check table fail with error ADMIN CHECK TABLE bank2_accounts fails: Error 1105: no available connections，it is expected when tikv nemeses injection

What is changed and how does it work?

ignore the error code with this error message

Check List

Tests

• Unit test
• E2E test
• Manual test (add detailed scripts or steps below)
• No code

Code changes

• Has Go code change
• Has CI related scripts change
• Has Terraform scripts change

Side effects

• Breaking backward compatibility

Related changes

• Need to update the documentation

Does this PR introduce a user-facing change?:

NONE