Move i15_1.py from using device_factory to using DeviceManager

[Mark-Booth]

Fixes #1882

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 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 99.14%. Comparing base (9637758) to head (920218d).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #1890   +/-   ##
=======================================
  Coverage   99.14%   99.14%           
=======================================
  Files         304      304           
  Lines       11508    11509    +1     
=======================================
+ Hits        11410    11411    +1     
  Misses         98       98           

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[DominicOram]

Great, thank you! Some notes for future PRs:

• The PR title will be automatically used for release notes (https://github.com/DiamondLightSource/dodal/releases/tag/2.0.0). I think this title is fine but I would usually remove the #1882 bit at the beginning as it IMO makes the notes less readable
• It's a good habit to fill in the Instructions to reviewer on how to test: section on the PR. It gives other people in the wider DAQ team a fighting chance at reviewing it. In this case I would have written something like "Confirm dodal connect i15-1 works on main and on here and there are the same number of devices on both

Both nice to haves though, I'll change the title and merge for you