Enable gofumpt linter and cleanup formatting

[alexandear]

Description

The PR removes unnecessary empty lines and clean-ups code formatting. Additionally, enables gofumpt linter to ensure empty lines won't appear in the future.

Type of change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update
• Refactor

Version of Go used when building/testing:

• 1.22
• 1.23

How Has This Been Tested?

By running tests.

Checklist

• My code follows the style guidelines of this project
• I have performed a self-review of my code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes