Add login step for user in testAgentSecretWithoutAgentConnectPermission

Ensures the web client logs in as userWithoutConnect before attempting to access the agent-secret endpoint.

Author: adhamahmad

test/src/test/java/hudson/slaves/SlaveComputerTest.java

@@ -271,6 +271,8 @@ void testAgentSecretWithoutAgentConnectPermission() throws Exception {
         j.jenkins.setAuthorizationStrategy(authStrategy);
 
         JenkinsRule.WebClient wc = j.createWebClient();
+        wc.login(userWithoutConnect);
+
         // Expect 403 Forbidden
         FailingHttpStatusCodeException e = assertThrows(FailingHttpStatusCodeException.class, () -> {
             wc.goTo("computer/" + testAgent.getNodeName() + "/agent-secret", "text/plain");