fix(ui5-menu): prevent global line-height inheritance

[hinzzx]

Previously setting a line-height property on global level e.g body { line-height: 0.5rem } was being inherited by the ui5-menu and its ui5-menu-item's which was not convenient.

With this chnange we now prevent the global inheritance of the line-height with the following priority:

ui5-menu-item > ui5-menu > global (globally no longer takes effect), which means if a line-height is set to the ui5-menu, all of its children (ui5-menu-items) would receive the effect, but if a specific ui5-menu-item receives the property, it would take over.

For example, here all children, except the first one (which has explicitly set style="line-height: 0.5rem;") would have line-height of 1rem

	<ui5-menu style="line-height: 1rem;" header-text="Basic Menu with Items" id="menuBasic" opener="btnOpenBasic">
		<ui5-menu-item style="line-height: 0.5rem;" text="New File" icon="add-document"></ui5-menu-item>
		<ui5-menu-item text="New Folder" icon="add-folder" disabled></ui5-menu-item>
		<ui5-menu-item text="Save" icon="add-folder" disabled></ui5-menu-item>
	</ui5-menu>

Before

After

Fixes: #10754