Update tests to use absolute paths

Fixes gh-8260

itest/web/src/integration-test/java/org/springframework/security/integration/BasicAuthenticationTests.java

@@ -28,7 +28,7 @@ public class BasicAuthenticationTests extends AbstractWebServerIntegrationTests
 	@Test
 	public void httpBasicWhenAuthenticationRequiredAndNotAuthenticatedThen401() throws Exception {
 		MockMvc mockMvc = createMockMvc("classpath:/spring/http-security-basic.xml", "classpath:/spring/in-memory-provider.xml", "classpath:/spring/testapp-servlet.xml");
-		mockMvc.perform(get("secure/index"))
+		mockMvc.perform(get("/secure/index"))
 			.andExpect(status().isUnauthorized());
 	}
 

itest/web/src/integration-test/java/org/springframework/security/integration/ConcurrentSessionManagementTests.java

@@ -47,7 +47,7 @@ public class ConcurrentSessionManagementTests extends AbstractWebServerIntegrati
 
 		MockMvc mockMvc = createMockMvc("classpath:/spring/http-security-concurrency.xml", "classpath:/spring/in-memory-provider.xml", "classpath:/spring/testapp-servlet.xml");
 
-		mockMvc.perform(get("secure/index").session(session1))
+		mockMvc.perform(get("/secure/index").session(session1))
 			.andExpect(status().is3xxRedirection());
 
 		MockHttpServletRequestBuilder login1 = login()