unattended: Always set "media" as install-source for ISOs

Let's set "media" as installation source for all the ISOs, even the
net-installer ones, as this can be dealt with on osinfo-db side.

Reviewed-by: Cole Robinson <crobinso@redhat.com>
Signed-off-by: Fabiano Fidêncio <fidencio@redhat.com>

tests/cli-test-xml/compare/virt-install-osinfo-netinst-unattended.xml

@@ -13,7 +13,7 @@
     <type arch="x86_64" machine="q35">hvm</type>
     <kernel>/VIRTINST-TESTSUITE/vmlinuz</kernel>
     <initrd>/VIRTINST-TESTSUITE/initrd.img</initrd>
-    <cmdline>ks=file:/fedora.ks inst.repo=</cmdline>
+    <cmdline>ks=file:/fedora.ks</cmdline>
   </os>
   <features>
     <acpi/>

virtinst/install/unattended.py

@@ -315,12 +315,8 @@ def _lookup_rawscript(osinfo, profile, os_media):
 def prepare_install_script(guest, unattended_data,
         url, os_media, injection_method):
     def _get_installation_source(os_media):
-        # This is ugly, but that's only the current way to deal with
-        # netinstall medias.
         if not os_media:
             return "network"
-        if os_media.is_netinst():
-            return "network"
         return "media"
 
     rawscript = _lookup_rawscript(guest.osinfo,