Heidelberg: Revert pre-fill of streets and ignore timezone on Christmas tree collection parse

[DerDreschner]

During inspection of the failed CI pipeline on my last pull request (#3497 / #3498), I recognized that using CONFIG_FLOW_TYPES with a public method call has unexpected side effects. Whenever the file is being imported (e.g., by running test_sources.py or update_docu_links.py), the Source.get_available_streets() method is being called in order to fill the CONFIG_FLOW_TYPES dictionary even without access to values of the dictionary at all. This leads to unnecessary and maybe excessive calls to the public API. It's visible in this pipeline run here.

First, I thought about answering calls from both test/debug scripts with an empty list using this workaround:

import inspect

[...]

    @staticmethod
    def get_available_streets() -> list[str]:
        if ("update_docu_links.py" or "test_sources.py") in inspect.stack()[-1].filename:
            return list()

But, honestly, I'm pretty sure there may be cases the file is being imported by HA/HACS I'm not aware of right now. And checking the stack-trace on runtime in production environments is pretty nasty. Therefore, I decided to revert this change entirely. In case the street entered by the user isn't correct, I call the API anyway and present the result as suggestions.

Additionally, I ignore the local timezone information now when parsing the Christmas tree collection date in order to avoid shifting it to another date unexpectedly.

Sorry for any inconvenience I caused!

[5ila5]

Thanks for your contribution

Custom pre-filled configuration flow are still very bad. They were an afterthought when creating the config_flow as it is now.
I want to look into this sometime, but I currently lack the time to do so.