Don't assert specific devices for accessibility tests and use iOS 18 again. (#4741)

* Don't assert specific devices for accessibility tests.

It's not as critical as UI/Preview tests as nothing is snapshotted.

* Extend the timeout for accessibility tests.

They're slow 😅

* Drop back to iOS 18.5 for accessibility tests (for now).

AccessibilityTests/Sources/Application.swift

@@ -24,19 +24,9 @@ enum Application {
     }
     
     private static func checkEnvironments() {
-        let requirediPhoneSimulator = "iPhone17,3" // iPhone 16
-        let requiredOSVersion = 18
-        
-        let osVersion = ProcessInfo().operatingSystemVersion
-        guard osVersion.majorVersion == requiredOSVersion else {
-            fatalError("Switch to iOS \(requiredOSVersion) for these tests.")
-        }
-        
-        guard let deviceModel = ProcessInfo().environment["SIMULATOR_MODEL_IDENTIFIER"] else {
-            fatalError("Unknown simulator.")
-        }
-        guard deviceModel == requirediPhoneSimulator else {
-            fatalError("Running on \(deviceModel) but we only support \(requirediPhoneSimulator)")
+        guard UIDevice.current.userInterfaceIdiom == .phone else {
+            XCTFail("Accessibility tests should be run on a phone.")
+            fatalError("Accessibility tests should be run on a phone.")
         }
     }
 }