Switch klistwithoverflow flex-wrap style

[AlexVelezLl]

Description

Switch KListWithOverflow flex-wrap from wrap to nowrap. This will remove a small tick where, for at most 100ms, a second row of KListWithOverflow is visible. The overflow: visible is kept to prevent issues with the focus outline and popup elements rendered as children of the list.

Targeting develop as this introduces a subtle breaking change: Now the container needs to ensure a proper min-width value is set so that the list can shrink properly (previously this wasn't needed because flex-wrap: wrap already handled this need.

This breaks the LanguageSwitcherFooter component on Kolibri, given that there the container cannot provide a proper min-width value, so a proper fix should be opened there before merging this PR.

Before/after screenshots

Before:

Grabacion.de.pantalla.2026-06-08.a.la.s.3.26.15.p.m.mov

After:

Grabacion.de.pantalla.2026-06-08.a.la.s.3.27.24.p.m.mov

Changelog

• Description: Fixes a small tick where two rows can be seen for at most 100ms when resizing a KListWithOverflow component.
• Products impact: bugfix.
• Addresses: -.
• Components: KListWithOverflow.
• Breaking: yes
• Impacts a11y: no
• Guidance: Make sure KListWithOverflow's containers can calculate and ensure a proper min-width value so that the list can be shrunk.