test(WhenAnonymousUserOpenNotExistingPage): remove the test.

This test doesn't provide much value and it's better to remove it rather
than port to Robot Framework. Also, we already have the tests for
checking that 404 page is shown, so we won't miss the possible errors on
that page.

Addressed to #530

No functional changes.

Author: php-coder

src/test/config/testng.xml

@@ -19,12 +19,6 @@
 		</classes>
 	</test>
 
-	<test name="When anonymous user open not existing page">
-		<classes>
-			<class name="ru.mystamps.web.tests.cases.WhenAnonymousUserOpenNotExistingPage" />
-		</classes>
-	</test>
-	
 	<test name="When anonymous user register account">
 		<classes>
 			<class name="ru.mystamps.web.tests.cases.WhenAnonymousUserRegisterAccount" />