Avoid setup failure on missing timedatectl (#6169)

When timedatectl is not available (e.g. in minimal devcontainers),
the code currently fails to setup due to missing timedate service on
D-Bus. This change makes the code more robust by checking only checking
for the presence of the service if we actually going to use it.

supervisor/host/control.py

@@ -85,14 +85,13 @@ class SystemControl(CoreSysAttributes):
 
     async def set_timezone(self, timezone: str) -> None:
         """Set timezone on host."""
-        self._check_dbus(HostFeature.TIMEDATE)
-
         # /etc/localtime is not writable on OS older than 16.2
         if (
             self.coresys.os.available
             and self.coresys.os.version is not None
             and self.sys_os.version >= AwesomeVersion("16.2.dev20250814")
         ):
+            self._check_dbus(HostFeature.TIMEDATE)
             _LOGGER.info("Setting host timezone: %s", timezone)
             await self.sys_dbus.timedate.set_timezone(timezone)
             await self.sys_dbus.timedate.update()