[ty] Refine message for why a rule is enabled

[MichaReiser]

Summary

I find rule xx is enabled by default reads more natural than when omitting the word rule, now that the rule code is no longer prefixed with lint:

Test Plan

See snapshots

[github-actions]

mypy_primer results

Changes were detected when running on open source projects

hydra-zen (https://github.com/mit-ll-responsible-ai/hydra-zen)
- error[invalid-return-type] src/hydra_zen/wrapper/_implementations.py:945:16: Return type does not match returned value: Expected `DataClass_`, found `@Todo(unsupported type[X] special form) | (((...) -> Any) & dict[Unknown, Unknown]) | (DataClass_ & dict[Unknown, Unknown]) | (list[Any] & dict[Unknown, Unknown]) | dict[Any, Any] | (((...) -> Any) & list[Unknown]) | (DataClass_ & list[Unknown]) | list[Any] | (dict[Any, Any] & list[Unknown])`
+ error[invalid-return-type] src/hydra_zen/wrapper/_implementations.py:945:16: Return type does not match returned value: Expected `DataClass_`, found `@Todo(unsupported type[X] special form) | (((...) -> Any) & dict[Unknown, Unknown]) | (DataClass_ & dict[Unknown, Unknown]) | (list[Any] & dict[Unknown, Unknown]) | dict[Any, Any] | (((...) -> Any) & list[Unknown]) | (DataClass_ & list[Unknown]) | list[Any]`