Fix placement for --enable-online-update-mar UI

* Resave with glade 3.40, which did all the
  changes to the .ui file
* to be safe, explicitly hide the UI in the C++
  code when building without `--enable-online-update-mar`
  (UI wasn't shown in a quick test with qt6 even
  without that, but better be safe)

Addresses this issue mentioned in [1]:

> - Online Update".  (For non-GTK VCL backends, there's still a bug that
> the "Automatic Update" section on that options page is mixed into the
> traditional --enable-online-update options at the top of the page,
> instead of down at the bottom; fixing of
> cui/uiconfig/ui/optonlineupdatepage.ui welcome...)

[1] https://lists.freedesktop.org/archives/libreoffice/2023-December/091309.html

Change-Id: I2fadbb3b93206834b8c2c17cb540fb0b0687742b
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/160830
Reviewed-by: Stephan Bergmann <stephan.bergmann@allotropia.de>
Tested-by: Jenkins
diff --git a/cui/source/options/optupdt.cxx b/cui/source/options/optupdt.cxx
index 8ce74bb..e8f4ee2 100644
--- a/cui/source/options/optupdt.cxx
+++ b/cui/source/options/optupdt.cxx
@@ -124,6 +124,8 @@ SvxOnlineUpdateTabPage::SvxOnlineUpdateTabPage(weld::Container* pPage, weld::Dia
#if HAVE_FEATURE_UPDATE_MAR
    m_xMar->show();
    m_xEnableMar->set_sensitive(!officecfg::Office::Update::Update::Enabled::isReadOnly());
#else
    m_xMar->hide();
#endif
}

diff --git a/cui/uiconfig/ui/optonlineupdatepage.ui b/cui/uiconfig/ui/optonlineupdatepage.ui
index 74a76e8..e491816 100644
--- a/cui/uiconfig/ui/optonlineupdatepage.ui
+++ b/cui/uiconfig/ui/optonlineupdatepage.ui
@@ -1,5 +1,5 @@
<?xml version="1.0" encoding="UTF-8"?>
<!-- Generated with glade 3.38.2 -->
<!-- Generated with glade 3.40.0 -->
<interface domain="cui">
  <requires lib="gtk+" version="3.20"/>
  <object class="GtkFrame" id="OptOnlineUpdatePage">
@@ -520,7 +520,6 @@
        </child>
        <child>
          <object class="GtkFrame" id="frameMar">
            <property name="visible">False</property>
            <property name="can-focus">False</property>
            <property name="label-xalign">0</property>
            <property name="shadow-type">none</property>
@@ -551,6 +550,11 @@
              </object>
            </child>
          </object>
          <packing>
            <property name="expand">False</property>
            <property name="fill">True</property>
            <property name="position">4</property>
          </packing>
        </child>
      </object>
    </child>