Use config server for OAV config files

[jacob720]

Fixes DiamondLightSource/mx-bluesky#1448
Required by DiamondLightSource/mx-bluesky#1521

Instructions to reviewer on how to test:

1. Check OAV config is read through config server

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
• If changing the API for a pre-existing device, ensure that any beamlines using this device have updated their Bluesky plans accordingly
• Have the connection tests for the relevant beamline(s) been run via dodal connect ${BEAMLINE}

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 99.08%. Comparing base (690e423) to head (dcb61d1).

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1748      +/-   ##
==========================================
- Coverage   99.11%   99.08%   -0.04%     
==========================================
  Files         318      318              
  Lines       12361    12354       -7     
==========================================
- Hits        12252    12241      -11     
- Misses        109      113       +4     

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