vmm: fix clippy warning

[morningtzh]

This pull request addresses several Clippy warnings and improves overall code formatting. The changes include:

1. Replace Default::default() with specific struct's default() method where applicable.
2. Remove usage of expect() function to improve error handling.
3. Modify wildcard imports (*) to be more specific.
4. Remove set -x from shell scripts to reduce verbosity.

Additionally, the entire codebase has been reformatted using rustfmt for consistency.

These changes aim to improve code quality, readability, and adherence to Rust best practices. No functional changes have been made to the software.

Please review and let me know if any further modifications are needed.

[Burning1020]

LGTM