fix(ui5-date-range-picker): stabilize tests (#13432)

This PR stabilizes the ui5-date-range-picker Cypress tests by adding proper assertions to ensure elements exist before interacting with them.

Author: GDamyanov

packages/main/cypress/specs/DateRangePicker.cy.tsx

@@ -1394,10 +1394,18 @@ describe("DateRangePicker - Two Calendars Feature", () => {
 
 			cy.realPress("Space");
 
+			cy.get<DateRangePicker>("@dateRangePicker")
+				.ui5DateRangePickerGetCalendar()
+				.shadow()
+				.find("[ui5-monthpicker]")
+				.should("exist")
+				.should("not.have.attr", "hidden");
+
 			cy.get<DateRangePicker>("@dateRangePicker")
 				.ui5DateRangePickerGetCalendar()
 				.shadow()
 				.find(".ui5-cal-overlay-container")
+				.should("exist")
 				.should("not.have.class", "ui5-cal-overlay-hidden");
 		});
 	});

packages/main/cypress/support/commands/DateRangePicker.commands.ts

@@ -90,6 +90,7 @@ Cypress.Commands.add("ui5DateRangePickerClickDateInCalendar", { prevSubject: tru
 Cypress.Commands.add("ui5DateRangePickerVerifySelectedDatesInCalendar", { prevSubject: true }, (subject: JQuery<DateRangePicker>, calendarIndex: number) => {
 	cy.wrap(subject)
 		.ui5DateRangePickerGetDayPicker(calendarIndex)
+		.should("exist")
 		.shadow()
 		.find(".ui5-dp-item--selected")
 		.should("exist");