if we do not disable the storageselector with bind mounts,
it automatically sets the first storage which can hold
containers (because of allowBlank: false) and triggers
the dirty flag but clicking on reset does not delete
the value there
Signed-off-by: Dominik Csapak <d.csapak@proxmox.com>
the initial loading of the storage selector fires a 'change'
event via the 'onLoad' method of its parent class
at that point the value of the storage selector is empty,
and the callback function fails
