fix(ui5-search-field): correct scope select border and icon sizing

Suppress the Select component's bottom border gradient inside the
search field's scope dropdown, and let the search icons fill their
container instead of being clamped to 1rem.

The gradient was introduced for Horizon theme compliance (#13408) but
should not appear in ShellBar context. The fixed 1rem icon size
conflicted with the new container-query-based icon sizing (#13569),
which left search-related icons rendering smaller than intended.

Fixes #13605

Author: ivoplashkov

packages/fiori/src/themes/SearchField.css

@@ -87,6 +87,8 @@
 	--_ui5_select_label_color: var(--sapShell_TextColor);
 	/* Remove Select's default focus outline without affecting dropdown items */
 	--_ui5_input_focus_outline_color: transparent;
+	/* Suppress Select's bottom border gradient inside ShellBar search */
+	--_ui5_select_bottom_border_gradient: none;
 }
 
 [ui5-select]:hover:not(:active):not(:focus-within) {
@@ -261,8 +263,6 @@
 }
 .ui5-shell-search-field-icon::part(root) {
 	padding: var(--_ui5_search_icon_padding);
-	width: 1rem;
-	height: 1rem;
 	outline-offset: -0.125rem;
 }