Make the name of default Keystone site for Apache2 a platform option

Since at least Debian 9 (Stretch) the name of the relevant site has been
'wsgi-keystone' rather than 'keystone'. Then again, as of 21.04 Ubuntu
continues to use the old site name.

Tha relevant attribute is also set for RHEL so that recipe validation
doesn't fail due to missing resource name, even though the resource in
question is currently guarded by 'if platform_family?("debian")'.

Signed-off-by: Marek Szuba <m.szuba@gsi.de>
Change-Id: I34b342d0b51cd5e11b1e5de95578ac47939895f9

attributes/default.rb

@@ -154,6 +154,7 @@ when 'fedora', 'rhel' # :pragma-foodcritic: ~FC024 - won't fix this
         openstack-selinux
         python2-urllib3
       ),
+    'keystone_apache2_site' => 'keystone', # currently unused on RHEL
     'keystone_service' => 'openstack-keystone',
     'keystone_process_name' => 'keystone-all',
     'package_options' => '',
@@ -168,6 +169,7 @@ when 'debian'
         libapache2-mod-wsgi-py3
         python3-keystone
       ),
+    'keystone_apache2_site' => platform?('ubuntu') ? 'keystone' : 'wsgi-keystone',
     'keystone_service' => 'keystone',
     'keystone_process_name' => 'keystone-all',
     'package_overrides' => '',

recipes/server-apache.rb

@@ -90,7 +90,7 @@ service 'keystone' do
 end
 
 # disable default keystone config file from UCA package
-apache2_site 'keystone' do
+apache2_site platform_options['keystone_apache2_site'] do
   action :disable
   only_if { platform_family?('debian') }
 end