[aura] Menu bar buttons have box shadow

[sissbruecker]

Description

Menu bar buttons have a box shadow applied, which is quite noticable with the primary variant. The shadow is also there for the regular variant, but less pronounced.

Expected outcome

No box shadow.

Minimal reproducible example

<vaadin-menu-bar theme="primary warning"></vaadin-menu-bar>

Steps to reproduce

See above

Environment

Vaadin version(s): 25

Browsers

No response

[yuriy-fix]

Based on the discussion, the box-shadow should be applied to the menu-bar.