Secondary admin bar items wrap onto a second line instead of remaining aligned with the primary toolbar

[jns141191]

Summary

The secondary section of the WordPress admin toolbar (#wp-admin-bar-top-secondary) moves below the primary toolbar instead of remaining on the same row when there are many toolbar items or limited horizontal space.

Steps to Reproduce
1) Log in to the WordPress admin area.
2) Install or activate multiple plugins that add items to the admin toolbar.
3) Open any admin page (e.g. Plugins → Installed Plugins).
4) Reduce the available toolbar width (or have enough toolbar items so the first row becomes full).

Expected Result

The secondary toolbar (#wp-admin-bar-top-secondary) should remain aligned with the primary toolbar on the same horizontal row and should not wrap onto a second line.

Actual Result

The secondary toolbar (#wp-admin-bar-top-secondary) wraps onto a second line below the primary toolbar, increasing the height of the admin bar and affecting the overall layout.

Additional Information
I discovered this issue while testing https://core.trac.wordpress.org/ticket/65445, but it appears to be unrelated to that ticket.

Environment

WordPress 7.1 RC1
WordPress 7.0.3
Chrome 132
Windows 10

[sabernhardt]

This is already tracked on #28983.

[sabernhardt]

Duplicate of #28983.