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 (b73b770) to head (4bf48f8).
⚠️ Report is 2 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #2018   +/-   ##
=======================================
  Coverage   99.08%   99.09%           
=======================================
  Files         319      319           
  Lines       12416    12426   +10     
=======================================
+ Hits        12303    12313   +10     
  Misses        113      113           

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.