Refactor create_merge_request_dropdown.js
<!--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=356603) </details> <!--IssueSummary end--> The following discussion from !83426 should be addressed: - [ ] @thomasrandolph started a [discussion](https://gitlab.com/gitlab-org/gitlab/-/merge_requests/83426#note_884571667): (+1 comment) > You could condense this a bit with something like this: > > ```suggestion:-6+0 > this.unavailableButtonText.textContent = isLoading > ? __('Checking branch availability...') > : __('New branch unavailable'); > > this.unavailableButtonSpinner.classList.toggle('gl-display-none', !isLoading); > ``` > > To be clear, this is only a very small verbosity/succinctness/repetition improvement. If you prefer the `if`/`else` format, you can safely ignore this and it's totally fine! > > |:grey_question: [What is this](https://gitlab.com/thomasrandolph/reviews/wikis/Review-Metadata-Table)|| > |-|-| > | Type | **Nitpick** | > | Blocker | No | > | Tags | _minor_, _verbosity_, _repetition_ | > | Concern Level 1-10 | 2 |
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