A follow up to #54773 (#54846)

When a search box has an expandable input field and is in "button only" mode, provide a max-width for the button and take away 100px when the form is expanded to avoid text wrapping and overflow in narrow viewport widths.
When the search form is collapsed revert to max-width of 100% to ensure the button fills its container. The input is not there so we don't need the 100px.

packages/block-library/src/search/style.scss

@@ -55,11 +55,12 @@ $button-spacing-y: math.div($grid-unit-15, 2); // 6px
 		margin-left: 0;
 		// Prevent unintended text wrapping.
 		flex-shrink: 0;
-		// Ensure minimum input field width in small viewports.
+		max-width: 100%;
+	}
+
+	// Ensure minimum input field width in small viewports.
+	.wp-block-search__button[aria-expanded="true"] {
 		max-width: calc(100% - 100px);
-		&.has-icon {
-			max-width: 100%;
-		}
 	}
 }