Fix CAInstance.import_ra_cert for empty passwords

OpenSSL can't cope with empty files, add a newline after each password

https://pagure.io/freeipa/issue/6878

Reviewed-By: Jan Cholasta <jcholast@redhat.com>

ipaserver/install/cainstance.py

@@ -690,7 +690,7 @@ class CAInstance(DogtagInstance):
 
         Used when setting up replication
         """
-        with ipautil.write_tmp_file(password) as f:
+        with ipautil.write_tmp_file(password + '\n') as f:
             pwdarg = 'file:{file}'.format(file=f.name)
             # get the private key from the file
             ipautil.run([paths.OPENSSL,