Fix HEOS discovery error when previously ignored

[andrewsayre]

Proposed change

The HEOS discovery flow does not properly handle the scenario where discovery was previously ignored and the config entry data is not populated. This results in an unhandled exception that gets logged at startup. This change properly handles previously ignored discovery. Test has been added to cover this scenario.

Type of change

• Dependency upgrade
• 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 HEOS error in log, and cannot install integration either #140079
• This PR is related to issue:
• Link to documentation pull request:
• Link to developer documentation pull request:
• Link to frontend pull request:

Checklist

• The code change is tested and works locally.
• Local tests pass. Your PR cannot be merged unless tests pass
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• The code has been formatted using Ruff (ruff format homeassistant tests)
• Tests have been added to verify that the new code works.

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