Use "merge" `inherit_mode` for `Exclude` in RuboCop configuration

What does this MR do?

This allows to move permanent Excludes from todo files into the main configuration file.

Screenshots (strongly suggested)

n/a

Does this MR meet the acceptance criteria?

Conformity

• [-] Changelog entry
• Documentation (if required)
• Code review guidelines
• Merge request performance guidelines
• Style guides
• [-] Database guides
• [-] Separation of EE specific content