tests: Fix http static test failing on retry

- test_http_static.py: If namespace creation fails, try to delete the namespace and create it again
- vpp_qemu_utils.py: Added "isinstance()" to "delete_namespace()" to match "create_namespace()"

Type: test

Change-Id: I88ff7a36f5d52816fee16283efba6af025496491
Signed-off-by: adrianvillin <avillin@cisco.com>
diff --git a/test/vpp_qemu_utils.py b/test/vpp_qemu_utils.py
index e7e21a0..3a8fdc8 100644
--- a/test/vpp_qemu_utils.py
+++ b/test/vpp_qemu_utils.py
@@ -216,12 +216,16 @@
         raise Exception("Error disabling gso:", e.output)
 
 
-def delete_namespace(namespaces):
+def delete_namespace(ns):
     """delete one or more namespaces.
 
     arguments:
     namespaces -- a list of namespace names
     """
+    if isinstance(ns, str):
+        namespaces = [ns]
+    else:
+        namespaces = ns
     try:
         for namespace in namespaces:
             result = subprocess.run(