PF4-PageLayoutDemo: Dropdown should only have a border on the hover state (like in Core)

[jschuler]

Same as the kebab/menu icon (used on mobile view)

Parent issue:
#955

[jschuler]

Probably needs https://github.com/patternfly/patternfly-react/pull/954/files and then need to update the pagelayoutdemo to use the isPlain prop on the dropdown toggle

[matthewcarleton]

This is being fixed in this PR patternfly/patternfly#971 there should be no border at all for the plain dropdowns.

[jschuler]

Fixed with #954