I also added, non_part_of_directive_in_part: info to analysis_options.yaml. Now it's info not error, without this I cannot suppress error.

example analysis_options.yaml:

include: package:monolib_common/library.yaml

analyzer:
  enable-experiment:
    - macros
    - enhanced-parts
  errors:
    non_part_of_directive_in_part: info