IPMI Workaround "None" option should not be displayed and instead set when all other options are unset

[cpg1111]

Describe the bug
In the multiselect for IPMI workaround options, there is a None option displayed, the explicit None value is used so that the CLI may unset the default value. However, the UI should hide this option and set it as a value when all other options are unset.

maas-ui version
HEAD

MAAS version
HEAD

LP issue
lp1958173

To Reproduce
Steps to reproduce the behavior:

1. Add a machine with IPMI power management
2. Configure IPMI options
3. Notice the None workaround option

Expected behavior
All options except None are displayed and available for selection, if all of the displayed options are unset, the None option is selected.

Screenshots

Desktop (please complete the following information):

• OS: Ubuntu 21.10
• Browser Firefox
• Version HEAD

Additional context
N/A

[Caleb-Ellis]

@cpg1111 Is this something we can expect to be used in other multiselect power type fields or is this probably an IPMI-only thing? i.e. should we handle this dynamically or should we special-case IPMI here?

[cpg1111]

At least for now, this is unique to the IPMI workaround options. We don't use multiselect for other power types currently.