fix(query): useridentity hostname only support char %

[TCeason]

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Summary

1. username containing @ should not encode when record log or err msg

2. We disabled arbitrary hostnames when creating users last year pr https://github.com/datafuselabs/databend/pull/11818 so the user meta key can only be generated by username, and % is a default value in UserIdentity.

3. delete StageFileInfo::creator

Note:

Also, do not support localhost as hostname.

• Fixes #[Link the issue here]

Tests

• [ ] Unit Test
• [x] Logic Test
• [ ] Benchmark Test
• [ ] No Test - Explain why

Type of change

• [x] Bug Fix (non-breaking change which fixes an issue)
• [ ] New Feature (non-breaking change which adds functionality)
• [ ] Breaking Change (fix or feature that could cause existing functionality not to work as expected)
• [ ] Documentation Update
• [ ] Refactoring
• [ ] Performance Improvement
• [ ] Other (please describe):

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This change is