Perf improvements

[b-long]

Remove slow function

Explanation of removed function:

If the input is of type EncryptionConfig, it creates a new DecryptionConfig by copying the
relevant fields from the EncryptionConfig. We do this using a type switch 1, which might
be improved using a type assertion 2.

It also calls the inputValidation function, which converts the struct to a map using JSON
marshaling and unmarshaling, then iterates through the map to check for empty values.

Depending on client configuration / usage, we've observed ~7% performance improvement (without other changes) and ~13% performance improvement when massaging some of the calling code