Label enter-to-add behavior broken when filtering in 1.23.7

[loncardom]

Description

Description:
In Gitea version 1.22.1, when filtering for a label in the issue or pull request label selector, the first item would automatically be selected, and pressing Enter would add that label. This behavior is no longer functioning in version 1.23.7.

Steps to reproduce:

1. Open the issue or pull request label selector.
2. Search for a label.
3. In version 1.22.1, the first label would be auto-selected, and pressing Enter would add it.
4. In version 1.23.7, the first label appears to still be highlighted, but pressing Enter does not add it, and the user must manually click the label with the mouse to add it.

Expected behavior:
Ability to add the filtered labels by pressing Enter.

Actual behavior:
Users must click the filtered labels manually.

Version:
Gitea 1.23.7 (working fine in 1.22.1)

Additional Information:
This change seems to have been introduced after 1.22.1, and it affects both the issue and pull request label selectors. If that is too broad of a version range I can try to pin it down to a specific version.

Tested on https://demo.gitea.com/loncardom/test/issues/1 which is running 1.24.0 and the issue persists.

Gitea Version

1.23.7

Can you reproduce the bug on the Gitea demo site?

Yes

Log Gist

No response

Screenshots

The label bug appears to be highligted but pressing Enter does nothing

Git Version

No response

Operating System

No response

How are you running Gitea?

Running Gitea through docker, though this issue is reproducible on try.gitea.io

Database

None

[wxiaoguang]

-> Fix some dropdown problem on the issue sidebar #34308