Renovate Airvisual tests

[bachya]

Proposed change

The AirVisual test suite needed a little love. This PR cleans it up:

1. We ensure all tests finish with either data_entry_flow.FlowResultType.CREATE_ENTRY or data_entry_flow.FlowResultType.ABORT.
2. We remove various overlapping functionality (patching, etc.).
3. We rename some fixtures for maximum clarity.
4. Per recommendation, we move config entry migration tests into test_init.py.

In so doing, I discovered a bug where the config flow would "see" an API key even if that API key failed.

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: N/A
• This PR is related to issue: N/A
• Link to documentation pull request: N/A

Checklist

• The code change is tested and works locally.
• Local tests pass. Your PR cannot be merged unless tests pass
• There is no commented out code in this PR.
• I have followed the development checklist
• The code has been formatted using Black (black --fast homeassistant tests)
• Tests have been added to verify that the new code works.

If user exposed functionality or configuration variables are added/changed:

• Documentation added/updated for www.home-assistant.io

If the code communicates with devices, web services, or third-party tools:

• The manifest file has all fields filled out correctly.
  Updated and included derived files by running: python3 -m script.hassfest.
• New or updated dependencies have been added to requirements_all.txt.
  Updated by running python3 -m script.gen_requirements_all.
• For the updated dependencies - a link to the changelog, or at minimum a diff between library versions is added to the PR description.
• Untested files have been added to .coveragerc.

To help with the load of incoming pull requests:

• I have reviewed two other open pull requests in this repository.

[MartinHjelmare]

This looks like we can and are moving directly to the form of another step. That's not good. The form is private to its step method. We should only move to another step by awaiting that step method.

[bachya]

@MartinHjelmare Absolutely. Renovating the config flow itself will make this PR bigger; would you be open to approving this one's focus on tests, then I can follow up with an additional PR to fix ^^^?

[MartinHjelmare]

Ok, thanks!