Adjust unnapliable suggestions in expanded lines
What does this MR do?
When expanding diff lines and leaving suggestion comments,
eventually, they showed as unnapliable even with no changes in the diff. It happens given the DiffNote#supports_suggestion? check was being made at Suggestion#appliable? in the discussions iteration.
The problem with DiffNote#supports_suggestion? as it is, is that
it uses Position#diff_file, which has a RequestStore "cache".
So for instance, if we have 3 comments in expanded diff lines
for the same diff file, just the first expansion would be
considered (again, because of the RequestStore at Position#diff_file) , therefore, just the first suggestion within
this set of comments on expanded lines would be appliable.
All in all, we're able to simply remove this check from the
Suggestion#appliable? method given we already check if the note supports
suggestions upon creation (Suggestions::CreateService).
As an extra outcome, we'll submit less Gitaly requests.
Issue: #31356 (closed)