Follow-up from "Fix note creation error for SHA256 repositories"

Follow-up for !174154 (comment 2247733096)

is it worth having a feature spec to make sure that diff comments get posted correctly?

Proposal

• Add a feature spec to verify if diff comments are posted correctly for SHA256 repositories.
• Apply an additional check for diff note length (to prevent SHA256 hashes in SHA1 repositories) (see note)

Note: How to setup SHA256 repository in tests