What does this MR do?
It now uses the PushMessage that was originally for the Slack service. It has a presenter, because the links for Slack and Hipchat are different. This improves the flog score of HipchatService#create_push_message.
Are there points in the code the reviewer needs to double check?
I removed the ending whitespace for the messages in Hipchat. The new and removed branch/tag messages have an ending newline. I am not sure whether this is needed. The branch/tag update message did not have it.
Why was this MR needed?
For issue #3444 (closed), this improves the flog score.
What are the relevant issue numbers?
Screenshots (if relevant)