[fix][broker] Correct MockAlwaysExpiredAuthenticationState test impl

In c0f38a0, we cherry picked a commit that relied on
a feature not yet implemented in this branch. This commit fixes what that commit
broke.

pulsar-broker/src/test/java/org/apache/pulsar/broker/auth/MockAlwaysExpiredAuthenticationState.java

@@ -52,6 +52,8 @@ public String getAuthRole() throws AuthenticationException {
 
     @Override
     public AuthData authenticate(AuthData authData) throws AuthenticationException {
+        authenticationDataSource = new AuthenticationDataCommand(new String(authData.getBytes(), UTF_8));
+        authRole = provider.authenticate(authenticationDataSource);
         return null;
     }
 
@@ -76,7 +78,7 @@ public AuthenticationDataSource getAuthDataSource() {
 
     @Override
     public boolean isComplete() {
-        return true;
+        return authRole != null;
     }
 
     @Override