Fix smartthings doing I/O in the event loop to import platforms

[bdraco]

Proposed change

Long term, this should be refactored to remove the side effects in the init of DeviceBroker

fixes #116128

Type of change

• [ ] Dependency upgrade
• [x] Bugfix (non-breaking change which fixes an issue)
• [ ] New integration (thank you!)
• [ ] New feature (which adds functionality to an existing integration)
• [ ] Deprecation (breaking change to happen in the future)
• [ ] Breaking change (fix/feature causing existing functionality to break)
• [ ] Code quality improvements to existing code or addition of tests

Additional information

• This PR fixes or closes issue: fixes #
• This PR is related to issue:
• Link to documentation pull request:

Checklist

• [ ] The code change is tested and works locally.
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[home-assistant[bot]]

Hey there @andrewsayre, mind taking a look at this pull request as it has been labeled with an integration (smartthings) you are listed as a code owner for? Thanks!

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[bdraco]

Thanks