Skip devices expected to be off

[jacob720]

Fixes DiamondLightSource/crystallography-bluesky#30
Skips devices that we expect to be off. Attenuator is not off but is currently broken.

Instructions to reviewer on how to test:

1. Do dodal connect i15_1
2. Confirm all devices connect other than attenuator
3. checkout main, do another dodal connect i15_1
4. Confirm the devices skipped in this PR don't connect (clean, slits_1, xtal)

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 99.09%. Comparing base (257b180) to head (244a46d).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #2018   +/-   ##
=======================================
  Coverage   99.09%   99.09%           
=======================================
  Files         326      326           
  Lines       12507    12507           
=======================================
  Hits        12394    12394           
  Misses        113      113           

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[DominicOram]

Thanks. Can you add comments next to all the ones that are skipped about why? Once tht's done happy for you to merge