Simplify merge request creation from issue into one atomic operation
<!--IssueSummary start--> <details> <summary> Everyone can contribute. [Help move this issue forward](https://handbook.gitlab.com/handbook/marketing/developer-relations/contributor-success/community-contributors-workflows/#contributor-links) while earning points, leveling up and collecting rewards. </summary> - [Close this issue](https://contributors.gitlab.com/manage-issue?action=close&projectId=278964&issueIid=585026) </details> <!--IssueSummary end--> <!-- This template is a great use for issues that are feature::additions or technical tasks for larger issues.--> This feature enhancement proposal was created on behalf of a ~"GitLab Premium" [customer](https://gitlab.lightning.force.com/lightning/r/Account/001PL0000038QutYAE/view) (internal link) who provided their feedback in a [support ticket](https://gitlab.zendesk.com/agent/tickets/681156) (internal link) ### Proposal When [creating a merge request from an issue](https://docs.gitlab.com/user/project/merge_requests/creating_merge_requests/#from-an-issue), it involves multiple operations and page navigations: > The actual process of creating a merge request and branch is overly complicated leading to user errors. > > a) Click the first “Create merge request” button below the issue description. This displays a confirmation pop-up. > > b) Click the second “Create merge request” button on the pop-up. This creates the branch, but not the MR. > > c) The pop-up disappears and the user sees the “issue” page again, before the “New merge request” page is displayed. > > d) Scroll down passed the pre-filled MR fields to reveal the third “Create merge request” button at the bottom of the screen. Through following this process, the user is required to click `Create merge request` a total of three times to get their desired outcome. It is possible for user error, leading to duplicate branches being created for the issue. It would be beneficial to have this process be a single atomic operation that creates the branch and merge request with a single navigation. <!-- Use this section to explain the feature and how it will work. It can be helpful to add technical details, design proposals, and links to related epics or issues. --> <!-- Consider adding related issues and epics to this issue. You can also reference the Feature Proposal Template (https://gitlab.com/gitlab-org/gitlab/-/blob/master/.gitlab/issue_templates/Feature%20proposal%20-%20detailed.md) for additional details to consider adding to this issue. Additionally, as a data oriented organization, when your feature exits planning breakdown, consider adding the `What does success look like, and how can we measure that?` section. --> <!-- Label reminders Use the following resources to find the appropriate labels: - Use only one tier label choosing the lowest tier this is intended for - https://gitlab.com/gitlab-org/gitlab/-/labels - https://about.gitlab.com/handbook/product/categories/features/ -->
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