Fix telegram broadcast

[balloob]

Breaking change

Proposed change

Fixes #69445

Unable to test this myself. @wicol can you take a look?

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[balloob]

This is no longer necessary because it's done before calling async_setup_platform and is passed to async_setup_platform: https://github.com/home-assistant/core/blob/dev/homeassistant/components/telegram_bot/__init__.py#L322-L329

[balloob]

Moved this to the test_telegram_bot.py where it's actually used.