Implement robot unload for udc default state

[rtuck99]

• Fixes UDC Default State should unload the sample instead of raising an exception #1438

Link to dodal PR (if required): #N/A
(remember to update pyproject.toml with the dodal commit tag if you need it for tests to pass!)

Instructions to reviewer on how to test:

1. Do thing x
2. Confirm thing y happens

Checks for reviewer

• Would the PR title make sense to a user on a set of release notes

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 92.86%. Comparing base (e912733) to head (f77a582).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #1607   +/-   ##
=======================================
  Coverage   92.85%   92.86%           
=======================================
  Files         153      153           
  Lines        8638     8645    +7     
=======================================
+ Hits         8021     8028    +7     
  Misses        617      617           

Components	Coverage Δ
i24 SSX	78.60% <ø> (ø)
hyperion	98.22% <100.00%> (+<0.01%)	⬆️
other	98.33% <ø> (ø)

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[DominicOram]

Looks good, thank you!