Stop using shared aiohttp client session for Subaru integration

[G-Two]

Proposed change

• Changes aiohttp_client helper call from async_get_clientsession() to async_create_clientsession()
  • Underlying API uses cookies to store session IDs
  • Fixes bug when users have more than one config entry

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 Subaru integration - two cars overwrite each other's sensor values.  #133898 Subaru integration misassigns data between cars #109520
• This PR is related to issue:
• Link to documentation pull request:

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
• I have followed the perfect PR recommendations
• The code has been formatted using Ruff (ruff format 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.

To help with the load of incoming pull requests:

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

[frenck]

Hmm interesting, why is this happening and problematic in terms of code?

[G-Two]

The user has two separate accounts to control two separate cars. The Subaru API login only occurs once during the config entry setup. Since the integration is using a a shared aiohttp client session, the second login overrides the first login session cookies. Creating separate client sessions during config entry setup should prevent this.

Same bug in the HACS version of the integration: G-Two/homeassistant-subaru#30

[frenck]

Check I see 👍

Thanks for the PR and happy holidays! 🎄

../Frenck