Update treeview expand icon

[mcoker]

Updates the tree view expand icons to point right when collapsed, down when expanded.

The core change is patternfly/patternfly#8490

Just need to update the icon from down to right.

[coderabbitai]

🔗 Related PRs

#12365 - chore(ArrowRightIcon): Update any uses of FA arrow right icon to RH brand arrow right icon [merged]
#12368 - chore(CaretDownIcon): Replace all usages of CaretDownIcon with RhUiCaretDownIcon [merged]
#12479 - fix(HamburgerIcon): Replace HamburgerIcon with RhUiStorageFillIcon [closed]
#12480 - fix(EllipsisHIcon): Replace EllipsisHIcon with RhUiEllipsisHorizontalFillIcon [closed]
#12523 - fix(ExpandIcon): Replace ExpandIcon with RhUiExpandIcon [merged]

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