Replace instances of DropLab with GlDropdown Vue component in `comment_type_toggle.js` [RUN-AS-IF-FOSS]

What does this MR do?

• Separates the relevant code within the comment_form.vue component of the Notes app into a separate component for use within snippets and commits discussion pages. (Note: this was moved to a separate MR – !68505 (merged))
• Re-implements comment_type_toggle.js using this Vue component rather than the DropLab-based implementation.

Essentially the functionality remains identical. There is a small visual difference (see screenshots below). This merely updates the snippets and commits discussion pages to utilize the same Vue component for the "commit type" dropdown as the merge requests, epics, and issues pages so that we can deprecate the DropLab library.

Screenshots or Screencasts (strongly suggested)

before	after

How to setup and validate locally (strongly suggested)

1. Check out this branch
2. Visit a snippet page
3. Post a comment
4. Start a thread
5. Observe that these actions still work as they did before
6. Do the same with a commit discussion page

Does this MR meet the acceptance criteria?

Conformity

• I have self-reviewed this MR per code review guidelines.
• This MR does not harm performance, or I have asked a reviewer to help assess the performance impact. (Merge request performance guidelines)
• I have followed the style guides.

Availability and Testing

• I have added/updated tests following the Testing Guide, or it's not needed. (Consider all test levels. See the Test Planning Process.)
• I have tested this MR in all supported browsers, or it's not needed.

Related to #241800 (closed)