Create a Branch Modal : Visible label/form field are not associated

Issue Summary

The form control is not correctly associated with its visible label either explicitly or implicitly.

Element: Label for "Custom" menu button
Location: Below the "Repository" form field

Steps to Reproduce

1. Launch the URL
2. Navigate to the Branch type dropdown menu in the Create brach menu in the main content area.

Screenshot

Actual Results

In the Create branch section, when the assistive technology user navigates through the Branch type dropdown list but is unable to understand with which label the dropdown is associated too. The screen reader announces the list of options available in the menu but would not understand the meaning since no association is indicated.

The labels need to be explicitly associated with their respective form controls for assistive technologies to identify the label accurately and convey the information to the users.

Expected Results

The dropdown menu should announce the label it is associated with. For this case , when the users focus enter the Dropdown menu , it should announce content such as "Branch type , select the type of branch from the list of items". This will help the assistive technology user to understand the relation between the label and dropdown menu.

An working example could be found at:
https://www.w3.org/TR/wai-aria-practices-1.2/examples/combobox/combobox-select-only.html 

Workaround

Currently, there is no known workaround for this behaviour. A workaround will be added here when available.

Bug Ref: 734856