chore: clean up ASN-related code

[Ashka59]

This pull request performs minor code cleanups and modernization in the ASN-related classes:

• In AsnInfo.java, removed an unused import.
• In AsnInfoProviderImplTest.java, removed the 'public' modifier.
• In AsnInfoProviderImpl.java, applied several refactorings: (Renamed variables record to csvRecord, used pattern matching with instanceof for more concise type checks and casts, used _ for unused lambda and exception variables)

These changes improve code readability and maintainability without affecting functionality.

[jon-signal]

Thank you for the contribution. Since there are no real functional changes in here, we'll pass for now and will aim to do some tidying the next time we're working in this space.