Remove ament_clang_format from system tests

[nahueespinosa]

Related to #154.

Summary

The configuration for clang_format and clang_tidy was moved to the root of the repository in #133.
This patch removes the call to both ament_clang_format and ament_clang_tidy from the system test package.

Checklist

• Read the contributing guidelines.
• Configured pre-commit and ran colcon test locally.
• Signed all commits for DCO.
• Added tests (regression tests for bugs, coverage of new code for features).
• Updated documentation (as needed).
• Checked that CI is passing.