Fixed errcheck issues in server/channels/api4/usage_test.go (#28644)

Co-authored-by: Ben Schumacher <ben.schumacher@mattermost.com>

server/.golangci.yml

@@ -96,7 +96,6 @@ issues:
         channels/api4/team_local.go|\
         channels/api4/team_test.go|\
         channels/api4/upload_test.go|\
-        channels/api4/usage_test.go|\
         channels/api4/user.go|\
         channels/api4/user_local.go|\
         channels/api4/user_test.go|\