Align default SESSION_TIMEOUT with horizon's default

The SESSION_TIMEOUT parameter in horizon defaults to 3600. This updates
the default in our module to use the consistent default.

Change-Id: Icb609fad8ce95f867fe467064995e665e42f253c

manifests/init.pp

@@ -339,7 +339,7 @@
 #  [*session_timeout*]
 #    (optional) The session timeout for horizon in seconds. After this many seconds of inactivity
 #    the user is logged out.
-#    Defaults to 1800.
+#    Defaults to 3600.
 #
 #  [*token_timeout_margin*]
 #    (optional) A time margin in seconds to subtract from the real token's validity.
@@ -596,7 +596,7 @@ class horizon(
   $root_url                                         = $::horizon::params::root_url,
   Stdlib::Absolutepath $root_path                   = "${::horizon::params::static_path}/openstack-dashboard",
   $access_log_format                                = undef,
-  $session_timeout                                  = 1800,
+  $session_timeout                                  = 3600,
   $token_timeout_margin                             = 0,
   $timezone                                         = 'UTC',
   Boolean $secure_cookies                           = false,

releasenotes/notes/update-default-session_timeout-fb7b20f13967160f.yaml

@@ -0,0 +1,6 @@
+---
+upgrade:
+  - |
+    Default value of the ``horizon::session_timeout`` parameter has been
+    changed from `1800` to `3600`, to be aligned with the default value in
+    horizon.

spec/classes/horizon_init_spec.rb

@@ -72,7 +72,7 @@ describe 'horizon' do
           'OPENSTACK_KEYSTONE_DEFAULT_ROLE = "member"',
           'TIME_ZONE = "UTC"',
           "            'handlers': ['file'],",
-          'SESSION_TIMEOUT = 1800',
+          'SESSION_TIMEOUT = 3600',
           'TOKEN_TIMEOUT_MARGIN = 0',
           'COMPRESS_OFFLINE = True',
           "FILE_UPLOAD_TEMP_DIR = '/tmp'",