chore: code format with make build

[luohoufu]

What does this PR do

code format with make build

Rationale for this change

This pull request includes several minor changes that primarily involve the removal of unnecessary blank lines and the addition of missing blank lines for better code readability. Below is a summary of the most important changes:

Code readability improvements:

• cmd/echo_server/main.go: Added a missing blank line after variable declarations.
• cmd/kafka_consumer/main.go: Added a missing blank line after the package declaration.
• common/flow.go: Added a missing blank line before the nilIDFlowError variable declaration.
• common/role_mapping.go: Removed unnecessary blank lines within the file.
• common/strings.go: Removed an unnecessary blank line after the FaviconPath variable declaration.

Standards checklist

• The PR title is descriptive
• The commit messages are semantic
• Necessary tests are added
• Updated the release notes
• Necessary documents have been added if this is a new feature
• Performance tests checked, no obvious performance degradation