fixes junos_config to be idempotent when confirming a commit (#4946)

The junos_config module would always return true when confirming a commit
This changes the module to now check first making the feature idempontent

lib/ansible/modules/network/junos/junos_config.py

@@ -231,9 +231,8 @@ def zeroize_config(module, result):
     result['changed'] = True
 
 def confirm_config(module, result):
-    if not module.check_mode:
+    checkonly = module.check_mode
-        module.connection.commit_config()
+    result['changed'] = module.connection.confirm_commit(checkonly)
-    result['changed'] = True
 
 def run(module, result):
     if module.params['rollback']: