guest: Remove old xen acpi disabling

This is only for rhel5 vintage xen which is long out of support,
so drop it

virtinst/guest.py

@@ -925,16 +925,8 @@ class Guest(XMLBuilder):
         if not self.os.is_hvm():
             return
 
-        default = True
-        if (self._os_object.need_old_xen_disable_acpi() and
-            not self.conn.check_support(support.SUPPORT_CONN_CAN_ACPI)):
-            default = False
-
         if self.features.acpi == "default":
-            if default:
-                self.features.acpi = self.capsinfo.guest.supports_acpi()
-            else:
-                self.features.acpi = False
+            self.features.acpi = self.capsinfo.guest.supports_acpi()
         if self.features.apic == "default":
             self.features.apic = self.capsinfo.guest.supports_apic()
         if self.features.pae == "default":

virtinst/osdict.py

@@ -382,9 +382,6 @@ class _OsVariant(object):
     def is_windows(self):
         return self.get_typename() == "windows"
 
-    def need_old_xen_disable_acpi(self):
-        return self._is_related_to(["winxp", "win2k"], check_upgrades=False)
-
     def broken_x2apic(self):
         # x2apic breaks networking in solaris10
         # https://bugs.launchpad.net/bugs/1395217

virtinst/support.py

@@ -249,7 +249,6 @@ SUPPORT_CONN_DEFAULT_QCOW2 = _make(
     version="0.8.0", hv_version={"qemu": "1.2.0", "test": 0})
 SUPPORT_CONN_DEFAULT_USB2 = _make(
     version="0.9.7", hv_version={"qemu": "1.0.0", "test": 0})
-SUPPORT_CONN_CAN_ACPI = _make(hv_version={"xen": "3.1.0", "all": 0})
 SUPPORT_CONN_WORKING_XEN_EVENTS = _make(hv_version={"xen": "4.0.0", "all": 0})
 SUPPORT_CONN_SOUND_AC97 = _make(
     version="0.8.0", hv_version={"qemu": "0.11.0"})