Remove Babel requirement

Babel is not needed as requirement, remove it.

See also
http://lists.openstack.org/pipermail/openstack-discuss/2020-April/014227.html

Commit 36d46bb0b1 removed the
openstack.common.gettextutils module, which used the babel package.
Commit a8fb4e2587 removed the babel.cfg
file.
It is therefore not needed to mock babel.localedata.locale_identifiers
in _set_expected_languages.

Change-Id: I05eaaf39c706e8ef43fe06611ea825a145caf015

glance/tests/unit/common/test_wsgi.py

@@ -22,7 +22,6 @@ import os
 import socket
 from unittest import mock
 
-from babel import localedata
 import eventlet.patcher
 import fixtures
 from oslo_concurrency import processutils
@@ -45,13 +44,6 @@ class RequestTest(test_utils.BaseTestCase):
         if all_locales is None:
             all_locales = []
 
-        # Override localedata.locale_identifiers to return some locales.
-        def returns_some_locales(*args, **kwargs):
-            return all_locales
-
-        self.mock_object(localedata, 'locale_identifiers',
-                         returns_some_locales)
-
         # Override gettext.find to return other than None for some languages.
         def fake_gettext_find(lang_id, *args, **kwargs):
             found_ret = '/glance/%s/LC_MESSAGES/glance.mo' % lang_id

test-requirements.txt

@@ -5,9 +5,6 @@
 # Hacking already pins down pep8, pyflakes and flake8
 hacking>=3.0.1,<3.1.0 # Apache-2.0
 
-# For translations processing
-Babel!=2.4.0,>=2.3.4 # BSD
-
 # Needed for testing
 coverage!=4.4,>=4.0 # Apache-2.0
 ddt>=1.0.1 # MIT