MR Title should be Branch Name instead of First Commit Message

Proposal

Currently when creating a MR from a branch with multiple commits, the MR title will contain the first commit's commit message (truncated, with the full one in the Description). This does not fit workflows where a branch contains of multiple small commits and each commit only describes the changes of this commit.

e.g.

• Branch Name: feature/service-x
• Commit 1: split base service into separate parts
• Commit 2: created new service X to do Y
• Commit 3: updated integration tests for use case Z

Coming from Bitbucket, I'm used to the PR title being the branch name (dashes converted to spaces), and the PR Description being a list of all commit messages. This was a lot more helpful because the first commit often does not describe the whole feature.

It would be nice if Gitlab could change its default MR title too to just be the branch name.