Stop checking the error message in test_boot_with_low_ram

It fails if locale is not C or en.

Closes-bug: #1824795

Change-Id: Iaf9865e5280e5a71e623dc4fa0c91f16449167b1
Signed-off-by: Cédric Ollivier <ollivier.cedric@gmail.com>
diff --git a/tempest/api/compute/flavors/test_flavors_negative.py b/tempest/api/compute/flavors/test_flavors_negative.py
index 3a474e6..235049a 100644
--- a/tempest/api/compute/flavors/test_flavors_negative.py
+++ b/tempest/api/compute/flavors/test_flavors_negative.py
@@ -70,9 +70,7 @@
         self.assertEqual(min_img_ram, image['min_ram'])
 
         # Try to create server with flavor of insufficient ram size
-        self.assertRaisesRegex(lib_exc.BadRequest,
-                               "Flavor's memory is too small for "
-                               "requested image",
-                               self.create_test_server,
-                               image_id=image['id'],
-                               flavor=flavor['id'])
+        self.assertRaises(lib_exc.BadRequest,
+                          self.create_test_server,
+                          image_id=image['id'],
+                          flavor=flavor['id'])