Only pass --xcube-viewer-api-url in server mode

If running a container in batch mode, this argument is
superfluous.

Author: pont-us

xcengine/core.py

@@ -370,9 +370,16 @@ def run(
         command = (
             ["python", "execute.py"]
             + (["--batch"] if run_batch else [])
-            + (["--server"] if host_port is not None else [])
+            + (
+                [
+                    "--server",
+                    "--xcube-viewer-api-url",
+                    f"http://localhost:{host_port}",
+                ]
+                if host_port is not None
+                else []
+            )
             + (["--from-saved"] if from_saved else [])
-            + (["--xcube-viewer-api-url", f"http://localhost:{host_port}"])
         )
         run_args = dict(
             image=self.image, command=command, remove=False, detach=True