fix(ui5-select): correct Horizon popover styles (#5186)

Related to: #5008

Author: dobrinyonkov

packages/main/src/themes/SelectPopover.css

@@ -1,14 +1,3 @@
-.ui5-select-popover:not(.ui5-select-popover-valuestate) [ui5-li]:first-child::part(native-li)::after {
-	border-top-left-radius: var(--_ui5_select_option_focus_border_radius);
-	border-top-right-radius: var(--_ui5_select_option_focus_border_radius);
-}
-
-
-.ui5-select-popover [ui5-li]:last-child::part(native-li)::after {
-	border-bottom-left-radius: var(--_ui5_select_option_focus_border_radius);
-	border-bottom-right-radius: var(--_ui5_select_option_focus_border_radius);
-}
-
 .ui5-select-popover::part(content),
 .ui5-select-popover::part(header) {
 	padding: 0;