Revert "Cast automatically drop connection (#12635)"

[OttoWinter]

Description:

TL;DR; Revert #12635 as a temporary workaround for #12968.

Some cast devices restart at night and cause the max retries logic to stop the connection, thus breaking some cast devices every night. The original purpose of #12635 was to not have to many stale socket clients around, that error has been in the integration for a long time and didn't cause issues of the same kind of magnitude as #12968. So I propose that we revert the automatically dropping connections while keeping the good parts of it (PlatformNotReady) for now.

I'm working on a refactor for this platform where the entity is responsible for the pychromecast.Chromecast objects but haven't had enough time to get that fully tested and ready. I hope to get that in the next major release. (+ then probably the release after that hopefully an even bigger cast platform refactor that would also make the integration finally async-aware...)

Related issue (if applicable): fixes #12968

Example entry for configuration.yaml (if applicable):

media_player:
  - platform: cast

Checklist:

• The code change is tested and works locally.
• Local tests pass with tox. Your PR cannot be merged unless tests pass

If the code does not interact with devices:

• Tests have been added to verify that the new code works.

[balloob]

😢 always so many edge cases.