fix(virtsecrets): a secret's value never reaches the page

The edit dialog of a secret was filled with its current value, so every
readable secret's value was in the secrets page's HTML. A private
secret, or one with no value yet, cannot be read: its field held the
text "None", which is valid base64, and saving the dialog unchanged set
the secret to the three bytes it decodes to. The dialog now only writes
a new value: the field starts empty, is a password field and is
required. The page no longer reads secret values, and get_secret_value,
used only for that, is gone.

virtsecrets/views.py

@@ -42,16 +42,11 @@ def secrets(request, compute_id):
 
         for uuid in secrets:
             secrt = conn.get_secret(uuid)
-            try:
-                secrt_value = conn.get_secret_value(uuid)
-            except libvirtError:
-                secrt_value = None
             secrets_all.append(
                 {
                     "usage": secrt.usageID(),
                     "uuid": secrt.UUIDString(),
                     "usageType": secret_usage_types[secrt.usageType()],
-                    "value": secrt_value,
                 }
             )
         if request.method == "POST":