Fix issues seen in testing on beamline

[DominicOram]

Fixes #278

Instructions to reviewer on how to test:

1. Comment out the zocalo results and pin tip detect devices (see Fix i03 system tests #261)
2. Run python tests/system_tests/test_i03_system.py and confirm they pass

Checks for reviewer

• Would the PR title make sense to a scientist on a set of release notes
• If a new device has been added does it follow the standards

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (77cdfe9) 89.77% compared to head (9fafa14) 89.77%.
Report is 4 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #281   +/-   ##
=======================================
  Coverage   89.77%   89.77%           
=======================================
  Files          81       81           
  Lines        2993     2993           
=======================================
  Hits         2687     2687           
  Misses        306      306           

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[dperl-dls]

Looks good, devices successfully connect now, thanks!