Mx bluesky 1679 misc fixes from testing 1 6 5

[rtuck99]

Fixes misc issues from #1679

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!)

Addresses the following issues uncovered during testing:

• Synchrotron beam dump countdown is not ignored if commissioning mode is on
• If there is no visit when UDC ends (if for example UDC default state failed) then the supervisor exits
• _supervisor.py doesn't return current_visit in decode_and_execute, so final robot unload is recorded with no visit.
• assertion in ispyb_callback_base isinstance(SynchrotronMode) fails
• Supervisor failed to raise an alert while waiting for feedback, due to dict value type issue

Instructions to reviewer on how to test:

1. Tests pass
2. Functionality as described

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 92.89%. Comparing base (62c0c9a) to head (860fef9).

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1687      +/-   ##
==========================================
+ Coverage   92.87%   92.89%   +0.01%     
==========================================
  Files         155      155              
  Lines        8494     8502       +8     
==========================================
+ Hits         7889     7898       +9     
+ Misses        605      604       -1     

Components	Coverage Δ
i24 SSX	77.35% <ø> (ø)
hyperion	98.63% <100.00%> (+0.04%)	⬆️
other	98.30% <100.00%> (-0.01%)	⬇️

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