[Island Roads] Default 'CONFIRM Subject' to be a blank selection

[nephila-nacrea]

A 'Please select' option with a blank value is added under every group header in the dropdown; this is selected by default (under the relevant header) to force the admin user to choose a triage category (rather than it defaulting to the first category in the group).

[skip changelog]

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 82.61%. Comparing base (0291878) to head (9e5465d).
Report is 3 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #5188      +/-   ##
==========================================
+ Coverage   82.49%   82.61%   +0.11%     
==========================================
  Files         406      406              
  Lines       31723    31990     +267     
  Branches     5048     5110      +62     
==========================================
+ Hits        26171    26428     +257     
- Misses       4062     4071       +9     
- Partials     1490     1491       +1     

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[dracos]

This looks good, but almost all of the two halves of the IF are the same, so can we have a much smaller IF inside? It looks to me you only need to change the inmost option-related bit. IF IoW, print out blank; and the existing selected IF could be dropped entirely I think, as that only applies for IoW.
Also stick a required on the <select> (in general, that can be I think) :)

[nephila-nacrea]

This looks good, but almost all of the two halves of the IF are the same, so can we have a much smaller IF inside? It looks to me you only need to change the inmost option-related bit. IF IoW, print out blank; and the existing selected IF could be dropped entirely I think, as that only applies for IoW. Also stick a required on the <select> (in general, that can be I think) :)

@dracos Not sure I did it in quite the way you asked but it's compact and seems to work :-) Also added some tests.

[dracos]

Thanks, yep, looks good :)